Driving apparatus

ABSTRACT

A driving apparatus ( 100   u ) is provided with: a first base portion ( 110 - 1 ); a first stage portion ( 130 - 1 ); a first elastic portion ( 120 - 1 ) which has elasticity to displace the first stage portion in one direction (X axis); a second stage portion ( 130 - 2 ) which is disposed on the first stage portion and on which a driven object ( 12 ) is mounted; a second elastic portion ( 120 - 2 ) which has elasticity to displace the second stage portion in other direction (Y axis); a first applying device ( 141, 142, 143, 22 ) for applying a first excitation force for displacing the first stage portion such that the first stage portion is resonated in the one direction at a resonance frequency determined by the first stage portion and the first elastic portion; and a second applying device ( 161, 162, 22 ) for applying a second excitation force for displacing the second stage portion at a phase shifted by approximately 90 degrees from a phase of the displacement of the first stage portion such that the second stage portion is resonated in the other direction at a resonance frequency determined by the second stage portion and the second elastic portion.

TECHNICAL FIELD

The present invention relates to a driving apparatus for driving a probeor the like in a uniaxial direction or biaxial directions so that theprobe scans the surface or the like of a medium.

BACKGROUND ART

For example, the development of a probe memory has been advanced whichrecords data onto a recording medium or which reproduces the datarecorded on the recording medium by displacing a probe array including aplurality of probes along a recording surface of the recording medium.In such a probe memory, the location of the probe array with respect tothe recording medium (in other words, a position relation between theprobe array and the recording medium) is determined, for example, bydisplacing a stage provided with the probe array. In other words, thelocation of the probe array with respect to the recording medium isdetermined by the operations of a MEMS (Micro Electro Mechanical System)actuator which is provided with the stage and which can displace thestage.

As a specific structure for displacing the stage provided with the probearray, for example, a MEMS actuator disclosed in a non-patent document 1is listed as one example. In such a MEMS actuator, the stage isdisplaced by applying a force to the stage such that the stageoscillates at a relatively low frequency (more specifically, at afrequency lower than the minimum resonance frequency of a spring-masssystem including the stage). As described above, the reason why a forceis applied to the stage to oscillate the stage at a frequency lower thanthe minimum resonance frequency is because it is considered that if theforce is applied to the stage to oscillate the stage at a frequency neara resonance frequency, the gain of the oscillation (i.e. oscillationrange) becomes too large, or it becomes harder to control a position ata frequency higher than the resonance frequency, resulting in unstableoperations of the stage (i.e. operations of the MEMS actuator). By this,it is possible to stabilize the operations of the MEMS actuator.

Non-Patent document 1: Tatehiko Hasebe, Seiko Yamanaka, Takeshi Harada,Yasushi Mutou, “Development of wide lateral stroke electro-magneticactuator driven by low voltage”, IEEJ Sensors and Micromachines SocietySogo-Kenkyukai/Micromachines and Sensor systems Kenkyu-kai, No.MSS-06-12

DISCLOSURE OF INVENTION Subject to be Solved by the Invention

On the other hand, for the MEMS actuator, due to its small size, lowerpower consumption is desired. Moreover, in order to increase a recordingcapacity of the recording medium, it is aimed to increase its recordingdensity to be extremely high and to reduce a recording pitch to be onthe order of nanometers. When the data is recorded into such anultramicro area by using the probes, performances are influenced byslight distortion in the driving position of the stage and positionrepeatability. Thus, it is desired to displace the stage moreefficiently.

The above can be listed as one example of the subject to be solved bythe invention. It is therefore an object of the present invention toprovide, for example, a driving apparatus (i.e. MEMS actuator) which canrealize the lower power consumption and which can realize thestabilization of a drive position by displacing a stage moreefficiently.

The above object of the present invention can be achieved by a drivingapparatus provided with: a first base portion; a first stage portionwhich can be displaced; a first elastic portion which connects the firstbase portion and the first stage portion and which has elasticity todisplace the first stage portion in one direction; a second stageportion which is disposed on the first stage portion, on which a drivenobject is mounted, and which can be displaced; a second elastic portionwhich connects the first stage portion and the second stage portion andwhich has elasticity to displace the second stage portion in otherdirection which is substantially perpendicular to the one direction; afirst applying device for applying a first excitation force fordisplacing the first stage portion such that the first stage portion isresonated in the one direction at a resonance frequency determined bythe first stage portion and the first elastic portion; and a secondapplying device for applying a second excitation force for displacingthe second stage portion at a phase shifted by approximately 90 degreesfrom a phase of the displacement of the first stage portion such thatthe second stage portion is resonated in the other direction at aresonance frequency determined by the second stage portion and thesecond elastic portion.

The operation and other advantages of the present invention will becomemore apparent from the embodiment explained below.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram conceptually showing the structure of aferroelectric recording/reproducing apparatus in example.

FIG. 2 are a plan view and a cross sectional view conceptually showingone example of a recording medium used in the example.

FIG. 3 is a cross sectional view conceptually showing a data recordingoperation.

FIG. 4 is a cross sectional view conceptually showing a datareproduction operation.

FIG. 5 is a plan view conceptually showing the structure of a drivingapparatus in a first example.

FIG. 6 is a plan view conceptually showing an aspect when a stage of thedriving apparatus in the first example shown in FIG. 5 is displaced.

FIG. 7 is a plan view conceptually showing the structure of a drivingapparatus in which the stage is displaced by applying an excitationforce caused by an electromagnetic force to a base.

FIG. 8 is a plan view conceptually showing the structure of a drivingapparatus in which the stage is displaced by applying an excitationforce caused by an electrostatic force to the base.

FIG. 9 is a plan view conceptually showing the structure of a drivingapparatus in a second example.

FIG. 10 is a plan view conceptually showing the structure of a drivingapparatus in which the stage is displaced by applying the excitationforce caused by the electromagnetic force to two suspensions.

FIG. 11 is a plan view conceptually showing the structure of a drivingapparatus in which the stage is displaced by applying the excitationforce caused by the electrostatic force to the two suspensions.

FIG. 12 is a plan view conceptually showing the structure of a drivingapparatus in a third example.

FIG. 13 is a plan view conceptually showing the structure of a drivingapparatus in which the stage is displaced by applying the excitationforce caused by the electromagnetic force to the stage.

FIG. 14 is a plan view conceptually showing the structure of a drivingapparatus in which the stage is displaced by applying the excitationforce caused by the electrostatic force to the stage.

FIG. 15 is a plan view conceptually showing the structure of a drivingapparatus in a fourth example.

FIG. 16 is a plan view conceptually showing an aspect when the drivingapparatus in the fourth example operates.

FIG. 17 is a plan view conceptually showing the structure of a drivingapparatus in which the mass of the stage is adjusted.

FIG. 18 is a plan view conceptually showing a driving apparatus in afifth example.

FIG. 19 is a plan view conceptually showing one aspect when a firststage of the driving apparatus in the fifth example shown in FIG. 18 isdisplaced.

FIG. 20 is a plan view conceptually showing another aspect when thefirst stage of the driving apparatus in the fifth example shown in FIG.18 is displaced.

FIG. 21 is a plan view conceptually showing the structure of a drivingapparatus in which a second stage is displaced in a Y-axis direction byapplying the excitation force caused by the electromagnetic force to thefirst stage.

FIG. 22 is a plan view conceptually showing the structure of a drivingapparatus in which the second stage is displaced in the Y-axis directionby applying the excitation force caused by the electrostatic force tothe first stage.

FIG. 23 is a plan view conceptually showing the structure of a drivingapparatus provided with two types of driving sources for displacing thesecond stage in the Y-axis direction.

FIG. 24 is a plan view conceptually showing the structure of a drivingapparatus provided with a plurality of second stages on the first stage.

FIG. 25 is a plan view conceptually showing the structure of a drivingapparatus in a sixth example.

FIG. 26 is a plan view conceptually showing another structure of thedriving apparatus in the sixth example.

FIG. 27 is a plan view conceptually showing the structure of a drivingapparatus provided with the plurality of second stages on the firststage.

FIG. 28 is a plan view conceptually showing the structure of a drivingapparatus in a seventh example.

FIG. 29 is a plan view conceptually showing an aspect when the stage ofthe driving apparatus in the seven example shown in FIG. 28 isdisplaced.

FIG. 30 is a plan view conceptually showing trajectories of thedisplacement of a plurality of probes realized by a driving apparatus inan eighth example.

DESCRIPTION OF REFERENCE CODES

-   1 ferroelectric recording/reproducing apparatus-   12 probe-   30 recording medium-   100 driving apparatus-   110 base-   120 suspension-   130 stage-   141, 143 electrode-   142 piezoelectric element-   144 force transmission mechanism-   151 coil-   152 magnetic pole-   161, 162 electrode-   170 spring constant adjustment device-   171 member-   172 spring-   173 stage mass adjustment device-   180 driving source

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, as the best mode for carrying out the present invention, anexplanation will be given on embodiments of the driving apparatus of thepresent invention.

An embodiment of the driving apparatus of the present invention is adriving apparatus provided with: a first base portion; a first stageportion which can be displaced; a first elastic portion which connectsthe first base portion and the first stage portion and which haselasticity to displace the first stage portion in one direction; asecond stage portion which is disposed on the first stage portion, onwhich a driven object is mounted, and which can be displaced; a secondelastic portion which connects the first stage portion and the secondstage portion and which has elasticity to displace the second stageportion in other direction which is substantially perpendicular to theone direction; a first applying device for applying a first excitationforce for displacing the first stage portion such that the first stageportion is resonated in the one direction at a resonance frequencydetermined by the first stage portion and the first elastic portion; anda second applying device for applying a second excitation force fordisplacing the second stage portion at a phase shifted by approximately90 degrees from a phase of the displacement of the first stage portionsuch that the second stage portion is resonated in the other directionat a resonance frequency determined by the second stage portion and thesecond elastic portion.

According to the embodiment of the driving apparatus of the presentinvention, by the operation of the first applying device, the firstexcitation force is applied that allows the first stage portion directlyor indirectly connected to the first base portion (i.e. the fixed firstbase portion which is the foundation) through the first elastic portionincluding various springs to be resonated in the one direction (e.g.Y-axis direction) at the resonance frequency determined by the firststage portion and the first elastic portion. In other words, due to thefirst excitation force applied by the first applying device, the firststage portion is displaced (in other words, movable) to be resonated atthe resonation frequency. In addition, in the embodiment, by theoperation of the second applying device, the second excitation force isapplied that allows the second stage portion directly or indirectlyconnected to the first stage portion (i.e. the first stage portion whichis the foundation for the second stage portion) through the secondelastic portion including various springs to be resonated in the otherdirection (e.g. X-axis direction) at the resonance frequency determinedby the second stage portion and the second elastic portion. In otherwords, due to the second excitation force applied by the second applyingdevice, the second stage portion is displaced (in other words, movable)to be resonated at the resonation frequency.

At this time, the second excitation force is applied by the secondapplying device such that the phase of the resonance of the second stageportion in the other direction and the phase of the resonance of thefirst stage portion in the one direction are shifted by approximately 90degrees. As a result, the trajectory of the second stage portion mountedon the first stage portion (in other words, the driven object mounted onthe second stage portion) is a circular orbit.

As described above, in the driving apparatus in the embodiment, thefirst stage portion can be resonated in the one direction, and thesecond stage portion mounted on the first stage portion can be resonatedin the other direction. By this, it is possible to resonate and displacethe second stage portion mounted on the first stage portion in the onedirection and in the other direction. Namely, it is possible tobiaxially drive the driven object. In particular, it is possible tobiaxially drive the driven object such that the trajectory of thedisplacement of the driven object is the circular orbit.

Moreover, in the embodiment, when the first stage portion is displacedin the one direction, the characteristic of resonance is used. In thesame manner, when the second stage portion is displaced in the otherdirection, the characteristic of resonance is used. Here, the“resonance” is a phenomenon in which repetition or superposition ofinfinitesimal forces causes infinite displacement. Thus, even if thefirst excitation force which is necessary to displace the first stageportion in the one direction or the second excitation force which isnecessary to displace the second stage portion in the other direction isreduced, it is possible to increase the displacement range of the firststage portion or the second stage portion. In other words, it ispossible to relatively reduce the first excitation force necessary forthe displacement of the first stage portion in the one direction or thesecond excitation force necessary to displace the second stage portionin the other direction. Thus, it is also possible to reduce electricenergy which is necessary to apply the first excitation force necessaryfor the displacement of the first stage portion in the one direction orthe second excitation force necessary for the displacement of the secondstage portion in the other direction. Therefore, it is possible todisplace the first stage portion and the second stage portion moreefficiently, resulting in lower power consumption.

Incidentally, in the construction described in the aforementionedBackground Art, the stage portion is displaced such that the stageportion oscillates at a lower frequency than the minimum resonancefrequency. In the embodiment, however, for the purpose of lower powerconsumption, the first stage portion and the second stage portion aredisplaced such that the first stage portion and the second stage portionoscillate at the resonance frequency. Such lower power consumption canbe said to be particularly effective in a small apparatus such as a MEMSactuator.

In addition, in the driving apparatus in which the stage portion isdisplaced by using oscillation, the position (balance) of the stageportion is possibly distorted depending on a direction and a location onwhich the force applied to the stage portion acts. In other words, ifthe force is not applied to the center of gravity of the stage portion,the position of the stage portion is possibly distorted. Alternatively,if the force applied to the stage portion includes a rotationalcomponent, the position of the stage portion is possibly distorted. Thismay result in a loss of repeatability with respect to aspects of thedisplacement of the stage portion. In the embodiment, however, the freeor independent behavior of the oscillation system itself including thefirst stage portion and the first elastic portion, which is theresonance, is used to displace the first stage portion, so that it ispossible to maintain the stability of the position of the first stageportion. In the same manner, in the embodiment, the free or independentbehavior of the oscillation system itself including the second stageportion and the second elastic portion, which is the resonance, is usedto displace the second stage portion, so that it is possible to maintainthe stability of the position of the second stage portion. As a result,it is possible to preferably obtain the repeatability with respect toaspects of the displacement of the first stage portion and the secondstage portion.

Then, if a probe array as the driven object is disposed on the secondstage portion and if the recording medium is disposed to face the probearray, each of the plurality of probes included in the probe array canbe displaced at a desired position on the recording medium. As a result,it is possible to record data at the desired position on the recordingmedium or to reproduce the data recorded at the desired position on therecording medium. In particular, according to the driving apparatus inthe embodiment, the biaxial drive can be performed. Thus, it is possibleto record the data onto the substantially entire recording surface onthe recording medium, or to reproduce the data recorded on thesubstantially entire recording surface on the recording medium.

In one aspect of the embodiment of the driving apparatus of the presentinvention, it is further provided with a second base portion which isdisposed on the first stage portion, the second stage portion beingdisposed on the second base portion, the second elastic portionconnecting the second base portion and the second stage portion.

According to this aspect, even if the second stage portion is disposedon the second base portion disposed on the first stage portion, it ispossible to preferably receive the aforementioned various effects.

In another aspect of the embodiment of the driving apparatus of thepresent invention, the first applying device applies the firstexcitation force with a period according to the resonance frequencydetermined by the first stage portion and the first elastic portion, andthe second applying device applies the second excitation force with aperiod according to the resonance frequency determined by the secondstage portion and the second elastic portion.

According to this aspect, for example, if the resonance frequency is f0,at least one of the first excitation force and the second excitationforce is applied with a period of 1/f0 or with a period that is N timesor 1/N times the period of 1/f0 (wherein N is an integer of 1 or more).In other words, at least one of the first excitation force and thesecond excitation force is applied once in every period of 1/f or inevery period that is N times or 1/N times the period of 1/f0 (wherein Nis an integer of 1 or more). As a result, at least one of the firstexcitation force and the second excitation force is applied in timing toincrease or maintain the resonance in accordance with aspects of theresonance of the stage portion. By this the stage portion is displacedto be resonated at the resonance frequency. Therefore, it is possible topreferably receive the aforementioned various effects.

In another aspect of the embodiment of the driving apparatus of thepresent invention, at least one of the first applying device and thesecond applying device applies at least one of the first excitationforce and the second excitation force caused by a piezoelectric effect.

According to this aspect, for example, change of the shape of apiezoelectric element which is obtained by applying a voltage to thepiezoelectric element can be used as at least one of the firstexcitation force and the second excitation force. As a result, it ispossible to preferably receive the aforementioned various effects.

In another aspect of the embodiment of the driving apparatus of thepresent invention, at least one of the first applying device and thesecond applying device applies at least one of the first excitationforce and the second excitation force caused by an electromagneticforce.

According to this aspect, for example, the electromagnetic force whichis obtained by electromagnetic interaction between a magnetic fieldgenerated by applying an electric current to a coil and a magnetic poledisposed to be adjacent to the coil can be used as at least one of thefirst excitation force and the second excitation force. As a result, itis possible to preferably receive the aforementioned various effects.

In another aspect of the embodiment of the driving apparatus of thepresent invention, at least one of the first applying device and thesecond applying device applies at least one of the first excitationforce and the second excitation force caused by an electrostatic force.

According to this aspect, for example, the electrostatic force which isgenerated due to a potential difference between facing two electrodescan be used as at least one of the first excitation force and the secondexcitation force. As a result, it is possible to preferably receive theaforementioned various effects.

The operation and other advantages of the present invention will becomemore apparent from the examples explained below.

As explained above, according to the embodiment of the driving apparatusof the present invention, it is provided with the first base portion,the first stage portion, the first elastic portion, the first applyingdevice, the second stage portion, the second elastic portion, and thesecond applying device. Therefore, by displacing the stage moreefficiently and stably, it is possible to realize lower powerconsumption and position stabilization.

EXAMPLES

Hereinafter, examples of the driving apparatus of the present inventionwill be described with reference to the drawings.

(1) Information Recording/Reproducing Apparatus

Firstly, with reference to FIG. 1 to FIG. 4, an explanation will begiven on an information recording/reproducing apparatus provided withany of the examples of the driving apparatus of the present invention.Incidentally, here, an explanation will be given on a ferroelectricrecording/reproducing apparatus which performs a recording operation orreproduction operation on a recording medium 30 in which a ferroelectricsubstance is used as a recording material.

(1-1) Structure

Firstly, the structure of a ferroelectric recording/reproducingapparatus in the example will be explained with reference to FIG. 1.FIG. 1 is a block diagram conceptually showing the structure of aferroelectric recording/reproducing apparatus in example.

As shown in FIG. 1, a ferroelectric recording/reproducing apparatus 1 isprovided with a probe 12 which is close to or in contact with arecording medium 30 and which is provided for a driving apparatus (inother words, a MEMS actuator) 100; and the recording medium 30 which isdisposed at a position facing to the probe 12. Moreover, theferroelectric recording/reproducing apparatus 1 is provided with areturn electrode 11 for returning thereto a high-frequency signal forsignal reproduction, applied from the probe 12; an inductor L which isdisposed between the probe 12 and the return electrode 11; an oscillator13 which oscillates at a resonance frequency determined by the inductorL and a capacitance Cs in a site that is polarized in accordance withrecord information and that is formed in an outer layer of or within adielectric material 31 under the probe 12; an alternating current (AC)signal generator 16 for applying an alternating electric field which isto detect the state of polarization recorded in the dielectric material31; a record signal generator 17 for recording the polarization stateinto the dielectric material 31; a switch 18 for changing the outputs ofthe AC signal generator 16 and the record signal generator 17; a HPF(High Pass Filter) 15; a demodulator 19 for demodulating a FM signalmodulated by the capacitance corresponding to the polarization stateowned by the dielectric material 31 under the probe 12; a signaldetector 20 for detecting data from a demodulated signal; a trackingerror detector 21 for detecting a tracking error signal from thedemodulated signal; an actuator drive circuit 22 for controlling theoperations of the driving apparatus 100; and the like.

The probe 12 is connected to the oscillator 13 through the HPF 15, andit is connected to the AC signal generator 16 and the record signalgenerator 17 through the HPF 15 and the switch 18. Moreover, the probe12 functions as an electrode for applying an electric field to thedielectric material 31.

Incidentally, the probe 12 is disposed on a stage 130 provided for thedriving apparatus 100 described later, and the probe 12 can be planarlydisplaced along a recording surface of the recording medium 30. Thedisplacement operation of the probe 12 is performed under the control ofthe actuator drive circuit 22. Incidentally, the displacement operationof the probe 12 (in other words, the structure and operations of thedriving apparatus 100) will be detailed later.

The return electrode 11 is an electrode for returning thereto ahigh-frequency electric field applied to the dielectric material 31 fromthe probe 12 (i.e. a resonance electric field from the oscillator 13),and the return electrode 11 is disposed to surround the probe 12.Incidentally, the shape and placement of the return electrode 11 can bearbitrarily set as long as the high-frequency electric field returns tothe return electrode 11 without resistance.

Incidentally, in the examples, only one probe 12 is shown in FIG. 1 forsimplification of explanation; however, a plurality of probes 12 arepreferably provided in order to improve a recording speed and areproduction speed. In this case, a plurality of AC signal generators 16are provided in association with the respective probes 12. Moreover, aplurality of signal detectors 20 are provided in order to discriminatebetween reproduction signals corresponding to the AC signal generators16 on the signal detectors 20, and the signal detectors 20 obtainreference signals from the respective AC signal generators 16, therebyoutputting the corresponding reproduction signals.

The inductor L is disposed between the probe 12 and the return electrode11, and it is formed from, for example, a microstripline. A resonancecircuit 14 is constructed including the inductor L and the capacitanceCs. The inductance of the inductor L is determined such that thisresonance frequency is, for example, approximately 1 GHz.

The AC signal generator 16 applies an alternating electric field to amicro domain between the return electrode 11 and an electrode 32.Moreover, the ferroelectric recording/reproducing apparatus which uses aplurality of probes 12 performs synchronization by using the frequenciesof the alternating electric fields as reference signals, therebydiscriminating signals detected on the probes 12. The frequencies arecentered on about 100 kHz.

The oscillator 13 is an oscillator which oscillates at the resonancefrequency determined from the inductor L and the capacitance Cs. Theoscillation frequency varies depending on the change of the capacitanceCs. Therefore, FM modulation is performed in association with thechange, which is due to the alternating field, of the capacitance Csdetermined by the polarization state corresponding to the recorded data.By demodulating this FM modulation, it is possible to read the datarecorded on the recording medium 30.

Incidentally, as described in detail later, the probe 12, the returnelectrode 11, the oscillator 13, the inductor L, the HPF 15, and thecapacitance Cs in the dielectric material 31 constitute the resonancecircuit 14, and the FM signal amplified in the oscillator 13 isoutputted to the demodulator 19.

The record signal generator 17 generates a signal for recording andsupplies it to the probe 12 at the time of recording. This signal is notlimited to a digital signal and it may be an analog signal. The signalincludes various signals, such as audio information, video information,and digital data for a computer. Moreover, the AC signal superimposed onthe record signal is used to discriminate and reproduce the informationon each probe, as the reference signal at the time of signalreproduction.

The switch 18 selects the output such that the signal from the AC signalgenerator 16 is supplied to the probe 12 at the time of reproduction andthe signal from the record signal generator 17 is supplied to the probe12 at the time of recording. For this apparatus, a mechanical relay anda semiconductor circuit are used. The switch 18 is preferablyconstructed from the relay in the case of the analog signal, and thesemiconductor circuit in the case of the digital signal.

The HPF 15 includes an inductor and a condenser, and it is used to forma high pass filter for cutting off a signal system so that the signalsfrom the AC signal generator 16 and the record signal generator 17 donot interfere with the oscillation of the oscillator 13. The cutofffrequency is f=½π√ {LC}. Here, L is the inductance of the inductorincluded in the HPF 15, and C is the capacitance of the condenserincluded in the HPF 15. The frequency of the AC signal outputted fromthe AC signal generator 16 is about 100 KHz, and the oscillationfrequency of the oscillator 13 is about 1 GHz. Thus, the separation issufficiently performed on a first order LC filter. A higher-order filtermay be used, but that increases the number of elements and possiblyincreases the apparatus size.

The demodulator 19 demodulates the FM signal and reconstructs a waveformcorresponding to the polarization state of a site which is traced by theprobe 12. If the recorded data are digital data of “0” and “1”, thereare two types of frequencies to be modulated. By judging the frequency,the data reproduction is easily performed.

The signal detector 20 reproduces the recorded data from the signaldemodulated on the demodulator 19. As the signal detector 19, forexample, a lock-in amplifier is used, and coherent detection orsynchronized detection is performed on the basis of the frequency of thealternating electric field of the AC signal generator 16, to therebyreproduce the data. Incidentally, it is obvious that another phasedetection device may be used.

The tracking error detector 21 detects a tracking error signal forcontrolling the apparatus, from the signal demodulated on thedemodulator 19. The detected tracking error signal is inputted into atracking mechanism, for the control.

Next, one example of the recording medium 30 using the dielectricmaterial shown in FIG. 1 will be explained with reference to FIG. 2.FIG. 2 are a plan view and a cross sectional view conceptually showingone example of the recording medium 30 used in the example.

As shown in FIG. 2( a), the recording medium 30 has, for example, arectangular shape. By relatively displacing the aforementioned probe 12on the recording surface of the recording medium 30, the data isrecorded onto the recording medium 30, or the data recorded on therecording medium 30 is reproduced.

Moreover, as shown in FIG. 2( b), the recording medium 30 is formed suchthat the electrode 32 is laminated on a substrate 33 and that thedielectric material 31 is laminated on the electrode 32.

The substrate 33 is, for example, Si (silicon) which is a preferablematerial in its strength, chemical stability, workability, or the like.The electrode 32 is intended to generate an electric field between theprobe 12 (or the return electrode 11) and the electrode 32. By applyingthe electric field that is equal to or stronger than the coerciveelectric field of the dielectric material 31 to the dielectric material31, the polarization direction is determined. By determining thepolarization direction in accordance with the data, the recording isperformed.

The dielectric material 31 is formed by a known technology, such asspattering LiTaO₃ or the like which is a ferroelectric substance, ontothe electrode 32. Then, the recording is performed with respect to the Zsurface of LiTaO₃ in which the plus and minus surfaces of thepolarization have a 180-degree domain relation. It is obvious thatanother dielectric material may be used. In the dielectric material 31,the small polarization is formed at high speed by a voltage for datarecording, which is applied simultaneously with a direct current biasvoltage.

(1-2) Operation Principle

Next, with reference to FIG. 3 and FIG. 4, the operation principle ofthe ferroelectric recording/reproducing apparatus 1 in the example willbe explained. Incidentally, in the explanation below, one portion of theconstituent elements of the ferroelectric recording/reproducingapparatus 1 shown in FIG. 1 is extracted and explained.

(1-2-1) Recording Operation

Firstly, with reference to FIG. 3, the recording operation of theferroelectric recording/reproducing apparatus 1 in the example will beexplained. FIG. 3 is a cross sectional view conceptually showing thedata recording operation.

As shown in FIG. 3, by applying an electric field which exceeds thecoercive electric field of the dielectric material 31 between the probe12 and the electrode 32, the dielectric material 31 is polarized havinga direction corresponding to the direction of the applied electricfield. Then, by controlling an applied voltage to thereby change thepolarization direction, it is possible to record the predeterminedinformation. This uses such a characteristic that if an electric fieldwhich exceeds the coercive electric field of a dielectric substance isapplied to the dielectric substance (particularly, a ferroelectricsubstance), the polarization direction is reversed, and that thepolarization direction is maintained thereafter.

For example, it is assumed that the micro domain has downwardpolarization P when an electric field is applied which directs from theprobe 12 to the electrode 32, and that the micro domain has upwardpolarization P when an electric field is applied which directs from theelectrode 32 to the probe 12. This corresponds to the state that thedata information is recorded. If the probe 12 is displaced in anarrow-pointing direction by the operation of the driving apparatus 100,a detection voltage corresponds to the polarization P and is outputtedas a rectangular wave which swings up and down.

(1-2-2) Reproduction Operation

Next, with reference to FIG. 4, the reproduction operation of theferroelectric recording/reproducing apparatus 1 in the example will beexplained. FIG. 4 is a cross sectional view conceptually showing thedata reproduction operation.

The nonlinear dielectric constant of a dielectric substance changes inaccordance with the polarization direction of the dielectric substance.Moreover, the nonlinear dielectric constant of the dielectric substancecan be detected as a difference of the capacitance of the dielectricsubstance or a difference of the capacitance change when an electricfield is applied to the dielectric substance. Therefore, by applying anelectric field to the dielectric material and by detecting a differenceof the capacitance Cs or a difference of the change of the capacitanceCs in a certain micro domain of the dielectric material at that time, itis possible to read and reproduce the data recorded as the polarizationdirection of the dielectric material.

Specifically, firstly, as shown in FIG. 4, an alternating electric fieldfrom the not-illustrated AC signal generator 16 is applied between theelectrode 32 and the probe 12. The alternating electric field has anelectric field strength which does not exceed the coercive electricfield of the dielectric material 31, and it has a frequency of, forexample, approximately 100 kHz. The alternating electric field isgenerated mainly to discriminate the difference of the capacitancechange corresponding to the polarization direction of the dielectricmaterial 31. Incidentally, instead of the alternating electric field, adirect current bias voltage may be applied to form an electric field inthe dielectric material 31. The application of the alternating electricfield causes the generation of an electric field in the dielectricmaterial 31 of the recording medium 30.

Then, the probe 12 is brought closer to the recording surface until thedistance between the tip of the probe 12 and the recording surfacebecomes extremely small on the order of nanometers. In this condition,the oscillator 13 is driven. Incidentally, in order to detect thecapacitance Cs of the dielectric material 31 under the probe 12 highlyaccurately, it is preferable to bring the probe 12 in contact with thesurface of the dielectric material 31, i.e. the recording surface.However, even if the tip of the probe 12 is not brought in contact withthe recording surface, for example, if the tip of the probe 12 isbrought closer to the recording surface to the extent that it can besubstantially regarded as the contact, the reproduction operation (andmoreover, the aforementioned recording operation) can be performed.

Then, the oscillator 13 oscillates at the resonance frequency of theresonance circuit 14 which includes the capacitance Cs, which isassociated with the dielectric material 31 under the probe 12, and theinductor L as the constituent factors. The center frequency of theresonance frequency is set to approximately 1 GHz, as described above.

Here, the return electrode 11 and the probe 12 constitute one portion ofthe oscillation circuit 14 including the oscillator 13. Thehigh-frequency signal of approximately 1 GHz, which is applied to thedielectric material 31 from the probe 12, passes through the dielectricmaterial 31 and returns to the return electrode 11, as shown by solidlines in FIG. 4. By disposing the return electrode 11 in the vicinity ofthe probe 12 and shortening a feedback route to the oscillation circuit14 including the oscillator 13, it is possible to reduce noise (e.g. afloating capacitance component) entering the oscillation circuit 14.

In addition, the change of the capacitance Cs corresponding to thenonlinear dielectric constant of the dielectric material 31 is extremelysmall, and it is necessary to adopt a detection method having highdetection accuracy in order to detect this change. In a detection methodusing FM modulation, the high detection accuracy can be generallyobtained; however, it is necessary to further improve the detectionaccuracy in order to make it possible to detect the small capacitancechange corresponding to the nonlinear dielectric constant of thedielectric material 31. Thus, in the ferroelectric recording/reproducingapparatus 1 in the example (i.e. a recording/reproducing apparatus whichuses the SNDM principle), the return electrode 11 is located in thevicinity of the probe 12 to shorten the feedback route to theoscillation circuit 14 as much as possible. By this, it is possible toobtain extremely high detection accuracy, thereby detecting the smallcapacitance change corresponding to the nonlinear dielectric constant ofthe dielectric substance.

After the oscillator 13 is driven, the probe 12 is displaced in parallelwith the recording surface on the dielectric recording medium 30. Sincethe polarization state of the domain of the dielectric material 31 underthe probe 12 varies depending on the recorded signal, the nonlinearcomponent of the dielectric constant changes under the probe 12. If thenonlinear component of the dielectric constant changes, the phase of theresonance frequency, i.e. the oscillation frequency of the oscillator13, changes with respect to the alternating electric field. As a result,the oscillator 13 outputs a signal which is FM-modulated on the basis ofthe polarization state, i.e. the recorded data.

This FM signal is frequency-voltage-converted by the demodulator 19. Asa result, the change of the capacitance Cs is converted to the extent ofthe voltage. The change of the capacitance Cs corresponds to thenonlinear dielectric constant of the dielectric material 31, and thenonlinear dielectric constant corresponds to the polarization directionof the dielectric material 31, and the polarization directioncorresponds to the data recorded in the dielectric material 31.Therefore, the signal obtained from the demodulator 19 is such a signalthat the voltage changes in accordance with the data recorded on therecording medium 30. Moreover, the signal obtained from the demodulator19 is supplied to the signal detector 20 and, for example, coherentdetection or synchronized detection is performed to extract the datarecorded on the recording medium 30.

At this time, on the signal detector 20, the AC signal generated by theAC signal generator 16 is used as the reference signal. By this, forexample, even if the signal obtained from the demodulator 19 includesmany noises or even if the data to be extracted is weak, the data can beextracted highly accurately by performing the synchronization with thereference signal, as described later.

(2) Driving Apparatus

Next, with reference to FIG. 5 to FIG. 30, an explanation will be givenon the driving apparatus 100 for driving the plurality of probes 12provided for the ferroelectric recording/reproducing apparatus 1 in theexamples.

(2-1) Driving Apparatus Adopting Uniaxial Driving Method

Firstly, with reference to FIG. 5 to FIG. 17, of the driving apparatus100 in the examples, driving apparatuses adopting a uniaxial drivingmethod (specifically, a driving apparatus in a first example to adriving apparatus in a fourth example described later) will bedescribed. Incidentally, the driving apparatus adopting the uniaxialdriving method is a driving apparatus that can displace the probes 12along one axis (e.g. Y axis). In other words, the driving apparatusadopting the uniaxial driving method is a driving apparatus that canrealize the one-dimension displacement of the probes 12.

(2-1-1) First Example of Driving Apparatus

Firstly, with reference to FIG. 5 and FIG. 6, a driving apparatus 100 ain a first example will be explained. FIG. 5 is a plan view conceptuallyshowing the structure of the driving apparatus 100 a in the firstexample. FIG. 6 is a plan view conceptually showing an aspect when astage 130 of the driving apparatus 100 a in the first example shown inFIG. 5 is displaced.

As shown in FIG. 5, the driving apparatus 100 a in the first example isprovided with a base 110, two suspensions 120, a stage 130, an electrode141, a piezoelectric element 142, and an electrode 143.

To the base 110 which is fixed (in other words, which is fixed within asystem as being the driving apparatus 100 a), the two suspensions 120which extend in a longitudinal direction are fixed at their one edges.Each of the two suspensions 120 constitutes one specific example of the“elastic portion” of the present invention, and it is a member havingelasticity such as a spring made of, for example, silicon, copperalloys, iron-type alloys, other metal, resins, and the like. The twosuspensions 120 are fixed to the stage 130 at the other edges. In otherwords, the stage 130 is supported (or hung) by the two suspensions 120.The stage 130 can be displaced in a Y-axis direction due to theelasticity of the two suspensions 120; namely, the stage 130 isdisplaced in the Y-axis direction by the two suspensions 120, as shownin FIG. 6. Moreover, the aforementioned probes 12 (here, the pluralityof proves 12) are disposed on the stage 130. Moreover, the electrode 141is disposed to hold the piezoelectric element 142 between the electrode141 and the electrode 143 which is fixed to the base 110 and which isgrounded.

Incidentally, on the base 110, the aforementioned recording medium 30 ispreferably held. In other words, since the plurality of probes 12 aredisplaced by disposing the plurality of probes 12 on the stage 130, therecording medium 30 is preferably constructed to be fixed to the base110 (i.e. not to displace the recording medium 30).

Moreover, the base 110 may be constructed as a box-type case which isprovided with the two suspensions 120 and the stage 130 in its innerspace. In this case, various constituents of the ferroelectricrecording/reproducing apparatus 1 explained with reference to FIG. 1(excluding at least the probes 12) may be disposed within and on thebase 110 which is the box-type case. In other words, the ferroelectricrecording/reproducing apparatus 1 in the example may be constructed as acard-type memory or the like having the base 110 as the case.Furthermore, it may be also constructed such that the base 110 is amovable body supported or hung by the two suspensions 120.

Here, an explanation will be given on the operations of the drivingapparatus 100 a in the first example having the aforementionedstructure. A desired voltage is applied to the electrode 141 in desiredtiming from the actuator drive circuit 22. Due to the application of thevoltage to the electrode 141, the piezoelectric element 142 changes itsshape. Here, since the electrode 143 is fixed to the base 110, thechange of the shape of the piezoelectric element 142 is added as a forceto the base 110 through the electrode 143. In other words, in the firstexample, a force caused by the change of the shape of the piezoelectricelement 142 due to the application of the voltage (i.e. a piezoelectriceffect) is applied to the base 110.

Here, since the base 110 is semifixed and the force is applied at theresonance frequency of the movable body (the two suspensions 120 and thestage 130 in the first example) as described later, the base 110 rarelymoves or slightly oscillates even if the force is applied by thepiezoelectric element 142 to the base 110. Moreover, even if the base110 slightly oscillates, its frequency is sufficiently higher than thefrequency of the oscillation of the stage 130 (i.e. the resonancefrequency described later). In other words, the amplitude of theoscillation of the base 110 is sufficiently smaller than that of thestage 130.

On the other hand, the two suspensions 120 which are fixed to the base110 at the one edges start to oscillate in accordance with the forceapplied by the piezoelectric element 142 to the base 110. As a result,the stage 130 which is fixed to the other edges of the two suspensions120 oscillates (i.e. is displaced) in the Y-axis direction as shown inFIG. 6.

Incidentally, in the explanation below, the force applied to the base110 to displace the stage 130 (particularly, to oscillate the stage 130at the resonance frequency) will be referred to as an “excitationforce”.

In the first example, in particular, the actuator drive circuit 22applies a desired voltage to the electrode 141 in desired timing so asto apply the excitation force for oscillating (i.e. resonating) thestage 130 at the resonance frequency determined by the two suspensions120 and the stage 130. For example, if the mass of the stage 130 is mand a spring constant is k when the two suspensions 120 is regarded asone spring, the actuator drive circuit 22 applies the desired voltage tothe electrode 141 in the desired timing so as to apply the excitationforce for resonating the stage 130 at a frequency of √ (k/m) (or at afrequency 1/N times the frequency of √ (k/m) (wherein N is an integer of1 or more). In this case, the actuator drive circuit 22 preferablyapplies the desired voltage to the electrode 141 so as to apply theexcitation force to the base 110 in timing synchronized with theresonance frequency. In other words, if the resonance frequency is f0,the actuator drive circuit 22 preferably applies the desired voltage tothe electrode 141 such that the excitation force is applied to the base110 with a period of 1/f0 or with a period that is M times the period of1/f0 (wherein M is an integer of 1 or more). Moreover, the actuatordrive circuit 22 preferably applies the desired voltage to the electrode141 so as to apply the excitation force that can maintain thedisplacement of the stage 130 (i.e. the excitation force that can applya force acting in the same direction as the displacement direction ofthe stage 130). Of course, if it is desired that the displacement of thestage 130 is stopped (or if it is desired that a range of thedisplacement of the stage 130 is reduced or attenuated), obviously, itis preferable to apply the excitation force that can stop thedisplacement of the stage 130 (i.e. the excitation force that can applyto the stage 130 a force applying in the opposite direction of thedisplacement direction of the stage 130 or the excitation force that canapply to the stage 130 a force applying in the same direction as thedisplacement direction of the stage 130 in timing in which phases areshifted by 180 degrees).

As described above, in the first example, the excitation force isapplied to the base 110 in timing according to the resonance frequencydetermined by the two suspensions 120 and the stage 130. As a result,the driving apparatus 100 a in the first example can resonate the stage130 at the resonance frequency determined by the two suspensions 120 andthe stage 130. In other words, the stage 130 performs self-resonance.

Here, the “resonance” is a phenomenon in which repetition orsuperposition of infinitesimal forces causes infinite displacement.Thus, even if the excitation force is reduced which is applied to thebase 110 to displace the stage 130, it is possible to increase thedisplacement range of the stage 130. In other words, it is possible torelatively reduce the excitation force necessary for the displacement ofthe stage 130. Thus, it is also possible to reduce electric energy whichis necessary to apply the excitation force necessary for thedisplacement of the stage 130 to the base 110. Therefore, it is possibleto displace the stage 130 more efficiently, resulting in the lower powerconsumption of the driving apparatus 100 a.

In addition, in the driving apparatus in which the stage 130 isdisplaced by applying to the stage 130 a force having directionality,the position (balance) of the stage 130 is possibly distorted dependingon a direction and a location on which the force applied to the stage130 (specifically, the force applied to the stage 130 in accordance withthe excitation force) acts. For example, if the force is not applied tothe center of gravity of the stage 130, the position of the stage 130 ispossibly distorted. Alternatively, if the force applied to the stage 130includes a rotational component, the position of the stage 130 ispossibly distorted. This may result in a loss of repeatability withrespect to aspects of the displacement of the stage 130. However, thedriving apparatus 100 a in the first example adopts such a method thatthe behavior of the oscillation system including the stage 130 and thetwo suspensions 120, which is the resonance, is used to displace thestage 130 and to apply the excitation force to the base 110, so that itis possible to preferably maintain the stability of the position of thestage 130. As a result, it is possible to preferably obtain therepeatability with respect to aspects of the displacement of the stage130.

Moreover, as opposed to using a phenomenon in which the oscillation hasa high gain when the stage is oscillated at the resonance frequency, inthe first example, it is possible to reduce the magnitude of theexcitation force at each time by using the phenomenon in which theresonance is the superposition of infinitesimal forces. Thus, it ispossible to control the position of the stage 130 to be more stable.

Moreover, if the plurality of probes 12 are provided for the stage 130and if the recording medium 30 is disposed to face the plurality ofprobes 12, each of the plurality of probes 12 can be displaced to adesired position on the recording medium 30. As a result, it is possibleto record the data at the desired position on the recording medium 30 orto reproduce the data recorded at the desired position on the recordingmedium 30.

In addition, in the first example, the excitation force is applied tothe base 110. In other words, a driving source for applying theexcitation force (i.e. the electrode 141, the piezoelectric element 142,and the electrode 143) is fixed to the base 110. Therefore, it isunnecessary to provide a driving source fixed to the movable portionincluding the two suspensions 120 and the stage 130. This can relativelylimit or control the generation of a heat caused by the driving sourcein the movable portion including the two suspensions 120 and the stage130. As a result, it is possible to preferably limit or control anadverse effect of the heat on the movable portion including the twosuspensions 120 and the stage 130.

Moreover, since the excitation force is applied to the base 110, it isunnecessary to provide the driving source for the movable portionincluding the two suspensions 120 and the stage 130. Thus, it ispossible to apply the excitation force without increasing the mass ofthe movable portion including the two suspensions 120 and the stage 130.Therefore, it is possible to increase sensitivity related to thedisplacement of the stage 130.

Moreover, in the first example, the excitation force caused by thepiezoelectric effect is applied. Thus, it is possible to apply therelatively large excitation force while the amount of change of theshape of the piezoelectric element 142 (i.e. the amount of displacementof the piezoelectric element 142) is relatively small. In other words,it is possible to apply the large excitation force without excessivelyincreasing the amount of change of the shape of the piezoelectricelement 142 (i.e. the amount of displacement of the piezoelectricelement 142).

Incidentally, if the excitation force caused by the piezoelectric effectis applied, the excitation force may be applied intermittently. Forexample, as described above, if the resonance frequency is f0, theexcitation force may be applied once in every period of 1/f or in everyperiod that is M times the period of 1/f0 (wherein M is an integer of 2or more). Even in such construction, it is possible to preferablyresonate the stage 130 since the excitation force caused by thepiezoelectric effect is relatively large. On the other hand, theexcitation force is not necessarily applied all the time, so that it ispossible to further reduce the electric energy necessary for theapplication of the excitation force. However, it is obvious that theexcitation force may be applied with a period other than theaforementioned examples or all the time as long as the stage 130 can beresonated. Moreover, even if an excitation force caused by anelectromagnetic force or an electrostatic force is applied, theexcitation force may be applied intermittently, or the excitation forcemay be applied all the time. Even in such construction, it is possibleto properly receive the same effects as in the case where the excitationforce caused by the piezoelectric effect is applied intermittently. Thisholds true in a second example and the like explained below.

Incidentally, in the first example, since the stage 130 is resonated,the displacement velocity of the stage 130 varies sinusoidally. In otherwords, at the limit of the displacement range of the stage 130 (i.e. atthe position of the maximum displacement of the stage 130), thedisplacement direction of the stage 130 changes from a positivedirection to a negative direction (e.g. an upward direction in FIG. 5 toa downward direction in FIG. 5), or from the negative direction to thepositive direction (e.g. the downward direction in FIG. 5 to the upwarddirection in FIG. 5). Thus, from the viewpoint of performing the stablerecording operation and reproduction operation, it is preferable not toperform the recording operation and reproduction operation using theprobes 12 near the limit of the displacement range of the stage 130.This holds true in the second example and the like explained below.

Moreover, in the explanation of the driving apparatus 100 a in the firstexample described above, the stage 130 is displaced by applying theexcitation force caused by the piezoelectric effect to the base 110.However, in addition to or instead of the excitation force caused by thepiezoelectric effect, the excitation force caused by the electromagneticforce or the excitation force caused by the electrostatic force may beapplied to the base 110. Here, with reference to FIG. 7 and FIG. 8, anexplanation will be given on the structures of a driving apparatus 100 bin which the stage 130 is displaced by applying the excitation forcecaused by the electromagnetic force to the base 110 and a drivingapparatus 100 c in which the stage 130 is displaced by applying theexcitation force caused by the electrostatic force to the base 110. FIG.7 is a plan view conceptually showing the structure of the drivingapparatus 100 b in which the stage 130 is displaced by applying theexcitation force caused by the electromagnetic force to the base 100.FIG. 8 is a plan view conceptually showing the structure of the drivingapparatus 100 c in which the stage 130 is displaced by applying theexcitation force caused by the electrostatic force to the base 110.

As shown in FIG. 7, the driving apparatus 100 b is provided with thebase 110, the two suspensions 120, and the stage 130, as in the drivingapparatus 100 a. The driving apparatus 100 b is provided particularlywith a coil 151 and a magnetic pole 152 at least one of which is fixedto the base 110, instead of the electrode 141, the piezoelectric element142, and the electrode 143 provided for the driving apparatus 100 a. Tothe coil 151, a desired voltage is applied in desired timing from theactuator drive circuit 22. The application of the voltage to the coil151 causes electromagnetic interaction between the coil 151 and themagnetic pole 152. As a result, an electromagnetic force by theelectromagnetic interaction is generated. Here, since at least one ofthe coil 151 and the magnetic pole 152 is fixed to the base 110, a forcecaused by the electromagnetic force is applied to the base 110. In otherwords, in the driving apparatus 100 b, the force caused by theelectromagnetic force is applied to the base 110 as the excitationforce. As a result, the stage 130 oscillates (i.e. is displaced) in theY-axis direction.

Even in such a driving apparatus 100 b, it is possible to receivesubstantially the same effects as those received by the drivingapparatus 100 a in which the aforementioned excitation force caused bythe piezoelectric effect is applied to the base 110.

As shown in FIG. 8, the driving apparatus 100 c is provided with thebase 110, the two suspensions 120, and the stage 130, as in the drivingapparatus 100 a. The driving apparatus 100 c is provided particularlywith an electrode 161 and an electrode 162 which is fixed to the base110 and which is grounded, instead of the electrode 141, thepiezoelectric element 142, and the electrode 143 provided for thedriving apparatus 100 a. The electrode 161 and the electrode 162 aredisposed with a predetermined distance therebetween. To the electrode161, a desired voltage is applied in desired timing from the actuatordrive circuit 22. Here, due to a potential difference between theelectrode 161 and the electrode 162, an electrostatic force (in otherwords, Coulomb force) is generated between the electrode 161 and theelectrode 162. Here, since the electrode 162 is fixed to the base 110, aforce caused by the electrostatic force is applied to the base 110. Inother words, in the driving apparatus 100 c, the force caused by theelectrostatic force is applied to the base 110 as the excitation force.As a result, the stage 130 oscillates (i.e. is displaced) in the Y-axisdirection.

Even in such a driving apparatus 100 c, it is possible to receivesubstantially the same effects as those received by the drivingapparatus 100 a in which the aforementioned excitation force caused bythe piezoelectric effect is applied to the base 110.

Incidentally, considering that the base 110 rarely oscillates, thestructure for applying the excitation force to the base 110 does notrequire such a large force as the excitation force. Moreover, incomparison to the excitation force caused by the piezoelectric effectand the excitation force caused by the electromagnetic force, theexcitation force caused by the electrostatic force is generally small.Thus, the structure for applying the excitation force to the base 110preferably applies the excitation force caused by the electrostaticforce.

Incidentally, a combination of the actuator drive circuit 22, theelectrode 141, the piezoelectric element 142, and the electrode 143constitutes one specific example of the “applying device” of the presentinvention. Moreover, a combination of the actuator drive circuit 22, thecoil 151, and the magnetic pole 152 constitutes one specific example ofthe “applying device” of the present invention. Moreover, a combinationof the actuator drive circuit 22, the electrode 161, and the electrode162 constitutes one specific example of the “applying device” of thepresent invention.

(2-1-2) Second Example of Driving Apparatus

Next, with reference to FIG. 9, a driving apparatus 100 d in a secondexample will be explained. FIG. 9 is a plan view conceptually showingthe structure of the driving apparatus 100 d in a second example.Incidentally, the same constituents as those of the driving apparatus100 a in the first example described above (and moreover, the drivingapparatus 100 b and the driving apparatus 100 c) will carry the samereferential numerals, and the detailed explanation thereof will beomitted.

As shown in FIG. 9, the driving apparatus 100 d in the second example isprovided with the base 110, the two suspensions 120, the stage 130, andtwo pairs of electrodes 141, piezoelectric elements 142, and electrodes143, which correspond to the two suspensions, as in the drivingapparatus 100 a in the first example.

In the driving apparatus 100 d in the second example, in particular, theexcitation force caused by the change of the shape of the piezoelectricelement 142 due to the application of the voltage (i.e. thepiezoelectric element) is applied to the two suspensions 120 instead ofthe base 110. Moreover, the driving apparatus 100 d is provided with twopairs of force transmission mechanisms 144 for amplifying the amount ofdisplacement by the excitation force. The force transmission mechanism144 uses the principle of leverage and is adapted to amplify the amountof displacement by the excitation force to several times to several tentimes. Moreover, even in the driving apparatus 100 d in the secondexample, as in the driving apparatus 100 a in the first example, theexcitation force that can displace the stage 130 is applied in timingaccording to the resonance frequency determined by the two suspensions120 and the stage 130. By this, the two suspensions 120 to which theexcitation force is applied start to oscillate. As a result, the stage130 which is fixed to the other edges of the two suspensions 120 isresonated (i.e. is displaced) in the Y-axis direction.

By this, even in the driving apparatus 100 d in the second example, itis possible to receive the same effects as those received by the drivingapparatus 100 a in the first example. In other words, it is possible toreduce the electric energy which is necessary to apply the excitationforce necessary for the displacement of the stage 130 to the twosuspensions 120. Therefore, it is possible to displace the stage 130more efficiently, resulting in the lower power consumption of thedriving apparatus 100 d. Moreover, since the behavior of the oscillationsystem including the stage 130 and the two suspensions 120, which is theresonance, is used to displace the stage 130, it is possible topreferably maintain the stability of the position of the stage 130. As aresult, it is possible to preferably obtain the repeatability withrespect to aspects of the displacement of the stage 130. As a result, itis possible to record the data at a desired position on the recordingmedium 30, or to reproduce the data recorded at the desired position onthe recording medium 30.

In addition, in the driving apparatus 100 d in the second example, theexcitation force is applied to the two suspensions 120. Here, if pointsof the two suspensions 120 to which the excitation force is applied areregarded as points of effort, if points of the two suspensions 120 towhich the base 110 is fixed are regarded as the fulcrums, and if pointsof the two suspensions 120 to which the stage 130 is fixed are regardedas points of load, it can be seen that the stage 130 is resonated byusing the principle of leverage. In other words, in the drivingapparatus 100 d in the second example, the two suspensions 120 are usedas levers. By this, by virtue of the excitation force that realizes theamount of displacement that is relatively small, it is possible todisplace the stage 130 relatively greatly.

Considering that the two suspensions 120 are used as levers, asdescribed above, a distance between the points to which the excitationforce is applied and the points at which the two suspensions 120 and thestage 130 are fixed is preferably greater than a distance between thepoints to which the excitation force is applied and the points at whichthe two suspensions 120 and the base 110 are fixed. In other words, thepoints to which the excitation force is applied are preferably close tothe points at which the two suspensions 120 and the base 110 are fixed.As the points to which the excitation force is applied are closer to thepoints at which the two suspensions 120 and the base 110 are fixed, itis possible to displace the stage 130 relatively greatly by theexcitation force that realizes the smaller amount of displacement.

Incidentally, from the viewpoint that the excitation force is simplyapplied, the driving apparatus 100 d in the second example is notnecessarily provided with the force transmission mechanisms 144.However, considering that the amount of change of the shape of thepiezoelectric element 142 due to the application of the voltage isrelatively small and that it is necessary to actually oscillate (i.e.displace) the two suspensions 120 by the excitation force, it ispreferable to amplify the amount of change of the shape of thepiezoelectric element 142 by using the force transmission mechanisms 144and to apply the excitation force caused by the amplified amount ofchange to the two suspensions 120.

Incidentally, in the second example, the stage 130 is displaced byapplying the excitation force caused by the piezoelectric effect to thetwo suspensions 120. However, even in the second example, as in thefirst example, in addition to or instead of the excitation force causedby the piezoelectric effect, the excitation force caused by theelectromagnetic force and the excitation force caused by theelectrostatic force may be applied to the two suspensions 120. Here,with reference to FIG. 10 and FIG. 11, an explanation will be given on adriving apparatus 100 e in which the stage 130 is displaced by applyingthe excitation force caused by the electromagnetic force to the twosuspensions 120 and a driving apparatus 100 f in which the stage 130 isdisplaced by applying the excitation force caused by the electrostaticforce to the two suspensions 120. FIG. 10 is a plan view conceptuallyshowing the structure of the driving apparatus 100 e in which the stage130 is displaced by applying the excitation force caused by theelectromagnetic force to two suspensions 120. FIG. 11 is a plan viewconceptually showing the structure of the driving apparatus 100 f inwhich the stage 130 is displaced by applying the excitation force causedby the electrostatic force to the two suspensions 120.

As shown in FIG. 10, the driving apparatus 100 e is provided with twopairs of coils 151 and magnetic poles 152 at least one of which is fixedto the corresponding suspension 120 of the two suspensions 120, insteadof the two pairs of electrodes 141, piezoelectric elements 142,electrodes 143, and force transmission mechanisms 144 which are providedfor the driving apparatus 100 d, as in the aforementioned drivingapparatus 100 b. In this case, the other of the coil 151 and themagnetic pole 152 that are not fixed to the corresponding suspension 120may be fixed to the base 110. To each of the coils 151, a desiredvoltage is applied in desired timing from the actuator drive circuit 22.By this, in the driving apparatus 100 e, a force caused by theelectromagnetic force is applied to the two suspensions 120 as theexcitation force. As a result, the stage 130 oscillates (i.e. isdisplaced) in the Y-axis direction. Even in such a driving apparatus 100e, it is possible to receive substantially the same effects as thosereceived by the driving apparatus 100 d in which the aforementionedexcitation force caused by the piezoelectric effect is applied to thetwo suspensions 120.

As shown in FIG. 11, the driving apparatus 100 f is provided with aplurality of electrodes 161 each of which is fixed to the base 110 and aplurality of electrodes 162 each of which is fixed to the correspondingsuspension 120 of the two suspensions 120 and each of which is grounded,instead of the two pairs of electrodes 141, piezoelectric elements 142,electrodes 143, and force transmission mechanisms 144 which are providedfor the driving apparatus 100 d, as in the aforementioned drivingapparatus 100 c. In particular, one of the plurality of electrodes 162arranged in a comblike manner is disposed between two of the pluralityof electrodes 161 arranged in a comblike manner. To each of theplurality of electrodes 161, a desired voltage is applied in desiredtiming from the actuator drive circuit 22. By this, in the drivingapparatus 100 f, a force caused by the electrostatic force is applied tothe two suspensions 120 as the excitation force. As a result, the stage130 oscillates (i.e. is displaced) in the Y-axis direction. Even in sucha driving apparatus 100 f, it is possible to receive substantially thesame effects as those received by the driving apparatus 100 d in whichthe aforementioned excitation force caused by the piezoelectric effectis applied to the two suspensions 120.

(2-1-3) Third Example

Next, with reference to FIG. 12, a driving apparatus 100 g in a thirdexample will be explained. FIG. 12 is a plan view conceptually showingthe structure of the driving apparatus 100 g in the third example.Incidentally, the same constituents as those of the driving apparatus100 a in the first example described above (and moreover, the drivingapparatus 100 b and the driving apparatus 100 c) and the drivingapparatus 100 d in the second example (and moreover, the drivingapparatus 100 e and the driving apparatus 100 f) will carry the samereferential numerals, and the detailed explanation thereof will beomitted.

As shown in FIG. 12, the driving apparatus 100 d in the third example isprovided with the base 110, the two suspensions 120, the stage 130, andthe two pairs of electrodes 141, piezoelectric elements 142, electrodes143, and force transmission mechanisms 144, as in the driving apparatus100 d in the second example.

In the driving apparatus 100 g in the third example, in particular, theexcitation force caused by the change of the shape of the piezoelectricelement 142 due to the application of the voltage (i.e. thepiezoelectric element) is applied directly to the stage 130 instead ofthe base 110 and the two suspensions 120. Moreover, even in the drivingapparatus 100 g in the third example, the excitation force is appliedthat can resonate the stage 130 at the resonance frequency determined bythe two suspensions 120 and the stage 130, as in the driving apparatus100 a in the first example and the driving apparatus 100 d in the secondexample. By this, the stage 130 to which the excitation force is appliedis resonated (i.e. is displaced) in the Y-axis direction.

By this, even in the driving apparatus 100 g in the third example, it ispossible to receive the same effects as those received by the drivingapparatus 100 a in the first example. In other words, it is possible toreduce the electric energy which is necessary to apply the excitationforce, which is necessary for the displacement of the stage 130, to thestage 130. Therefore, it is possible to displace the stage 130 moreefficiently, resulting in the lower power consumption of the drivingapparatus 100 g. Moreover, since the behavior of the oscillation systemincluding the stage 130 and the two suspensions 120, which is theresonance, is used to displace the stage 130, it is possible topreferably maintain the stability of the position of the stage 130. As aresult, it is possible to preferably obtain the repeatability withrespect to aspects of the displacement of the stage 130. As a result, itis possible to record the data at a desired position on the recordingmedium 30, or to reproduce the data recorded at the desired position onthe recording medium 30.

Moreover, since the excitation force is applied to the stage 130, if theexcitation force is applied in timing according to the displacement ofthe stage 130, i.e. intermittently, it is possible to resonate the stage130. Specifically, although the distance between the force transmissionmechanisms 144 and the stage 130 varies depending on the displacement ofthe stage 130, if the excitation force is applied when the forcetransmission mechanisms 144 and the stage 130 are in contact, it ispossible to resonate the stage 130. Thus, it is no longer necessary toapply the excitation force all the time, so that it is possible tofurther reduce the electric energy which is necessary to apply theexcitation force.

Incidentally, in the third example, the stage 130 is displaced byapplying the excitation force caused by the piezoelectric effect to thestage 130. However, even in the third example, in addition to or insteadof the excitation force caused by the piezoelectric effect as in thefirst and second examples, the excitation force caused by theelectromagnetic force and the excitation force caused by theelectrostatic force may be applied to the stage 130. Here, withreference to FIG. 13 and FIG. 14, an explanation will be given on adriving apparatus 100 h in which the stage 130 is displaced by applyingthe excitation force caused by the electromagnetic force to the stage130 and a driving apparatus 100 i in which the stage 130 is displaced byapplying the excitation force caused by the electrostatic force to thestage 130. FIG. 13 is a plan view conceptually showing the structure ofthe driving apparatus 100 h in which the stage 130 is displaced byapplying the excitation force caused by the electromagnetic force to thestage 130. FIG. 14 is a plan view conceptually showing the structure ofthe driving apparatus 100 i in which the stage 130 is displaced byapplying the excitation force caused by the electrostatic force to thestage 130.

As shown in FIG. 13, the driving apparatus 100 h is provided with twopairs of coils 151 and magnetic poles 152 at least ones of which arefixed to the stage 130, instead of the two pairs of electrodes 141,piezoelectric elements 142, electrodes 143, and force transmissionmechanisms 144 which are provided for the driving apparatus 100 g, as inthe driving apparatus 100 b and the driving apparatus 100 e describedabove. In this case, the others of the coil 151 and the magnetic pole152 that are not fixed to the stage 130 may be fixed to the base 110. Toeach of the coils 151, a desired voltage is applied in desired timingfrom the actuator drive circuit 22. By this, in the driving apparatus100 h, a force caused by the electromagnetic force is applied to thestage 130 as the excitation force. As a result, the stage 130 oscillates(i.e. is displaced) in the Y-axis direction. Even in such a drivingapparatus 100 h, it is possible to receive substantially the sameeffects as those received by the driving apparatus 100 g in which theaforementioned excitation force caused by the piezoelectric effect isapplied to the stage 130.

As shown in FIG. 14, the driving apparatus 100 i is provided with aplurality of electrodes 161 each of which is fixed to the base 110 and aplurality of electrodes 162 each of which is fixed to the stage 130 andeach of which is grounded, instead of the two pairs of electrodes 141,piezoelectric elements 142, electrodes 143, and force transmissionmechanisms 144 which are provided for the driving apparatus 100 g, as inthe driving apparatus 100 c and the driving apparatus 100 f describedabove. In particular, one of the plurality of electrodes 162 arranged ina comblike manner is disposed between two of the plurality of electrodes161 arranged in a comblike manner. To each of the electrodes 161, adesired voltage is applied in desired timing from the actuator drivecircuit 22. By this, in the driving apparatus 100 i, a force caused bythe electrostatic force is applied to the stage 130 as the excitationforce. Even in such a driving apparatus 100 i, it is possible to receivesubstantially the same effects as those received by the drivingapparatus 100 g in which the aforementioned excitation force caused bythe piezoelectric effect is applied to the stage 130.

(2-1-4) Fourth Example

Next, with reference to FIG. 15 and FIG. 16, a driving apparatus 100 jin a fourth example will be explained. FIG. 15 is a plan viewconceptually showing the structure of the driving apparatus 100 j in thefourth example. FIG. 16 is a plan view conceptually showing an aspectwhen the driving apparatus 100 j in the fourth example operates.Incidentally, the same constituents as those of the driving apparatus100 a in the first example described above (and moreover, the drivingapparatus 100 b and the driving apparatus 100 c), the driving apparatus100 d in the second example (and moreover, the driving apparatus 100 eand the driving apparatus 100 f), and the driving apparatus 100 g in thethird example (and moreover, the driving apparatus 100 h and the drivingapparatus 100 i) will carry the same referential numerals, and thedetailed explanation thereof will be omitted.

As shown in FIG. 15, the driving apparatus 100 j in the fourth exampleis provided with the base 110, the two suspensions 120, the stage 130,the plurality of electrodes 161 each of which is fixed to the base 110,and the plurality of electrodes 162 each of which is fixed to the stage130 and each of which is grounded, as in the driving apparatus 100 i inthe third example (refer to FIG. 14).

Particularly, the driving apparatus 100 j in the fourth example isprovided with two spring constant adjustment devices 170 correspondingto the two suspensions 120. Each of the two spring constant adjustmentdevices 170 is provided with a predetermined member 171 which can befreely attached to and detached from the corresponding suspension 120 ofthe two suspensions 120 and a spring 172 for applying a force to attachthe member 171 to the corresponding suspension 120 or to detach themember 171 from the corresponding suspension 120.

The spring 172 extends in response to a control signal outputted fromthe actuator drive circuit 22. As a result, the member 171 is attachedto the corresponding suspension 120. In other words, as shown in FIG.16, the member 171 and the corresponding suspension 120 are unified.This results in a change of the spring constant of each of the twosuspensions 120. On the other hand, the spring 172 contracts in responseto the control signal outputted from the actuator drive circuit 22. As aresult, the member 171 is detached from the corresponding suspension120. In other words, the member 171 and the corresponding suspension 120which are unified are detached. This results in a change of the springconstant of each of the two suspensions 120.

This changes the resonance frequency determined by the two suspensions120 and the stage 130, so that it is possible to resonate the stage 130at a desired frequency.

Incidentally, in addition to or instead of changing the resonancefrequency by adjusting the spring constant of the two suspensions 120,the mass of the stage 130 may be adjusted to change the resonancefrequency. Here, the structure of a driving apparatus 100 k in which themass of the stage 130 is adjusted will be explained with reference toFIG. 17. FIG. 17 is a plan view conceptually showing the structure ofthe driving apparatus 100 k in which the mass of the stage 130 isadjusted.

As shown in FIG. 17, the driving apparatus 100 k is provided with thebase 110, the two suspensions 120, the stage 130, the plurality ofelectrodes 161 each of which is fixed to the base 110, the plurality ofelectrodes 162 each of which is fixed to the stage 130 and each of whichis grounded, as in the aforementioned driving apparatus 100 j, and astage mass adjustment device 173. The stage mass adjustment device 173is provided with a predetermined member 171 which can be freely attachedto and detached from the stage 130 and a spring 172 for applying a forceto attach the member 171 to the stage 130 or to detach the member 171from the stage 130.

The spring 172 extends in response to a control signal outputted fromthe actuator drive circuit 22. As a result, the member 171 is attachedto the stage 130. In other words, the member 171 and the stage 130 areunified. This results in a change of the mass of the stage 130. On theother hand, the spring 172 contracts in response to the control signaloutputted from the actuator drive circuit 22. As a result, the member171 is detached from the stage 130. In other words, the member 171 andthe stage 130 which are unified are detached. This results in a changeof the mass of the stage 130.

This changes the resonance frequency determined by the two suspensions120 and the stage 130, so that it is possible to resonate the stage 130at a desired frequency.

Incidentally, in the fourth example, the spring 172 is presented as adriving force generation member for applying, to the member 171, theforce for attaching and detaching the member 171 with respect to thestage 130 or the corresponding suspension 120. Instead of the spring172, however, a driving force generation member which uses theelectrostatic force, the electromagnetic force, and the like may beadopted.

Incidentally, the aforementioned explanation describes the structurethat is realized by combining the constituents for adjusting theresonance frequency with respect to the driving apparatus 100 i in thethird example. However, it is obvious that the constituents foradjusting the resonance frequency may be combined with respect to theother driving apparatus 100 g or driving apparatus 100 h in the thirdexample. In the same manner, it is obvious that the constituents foradjusting the resonance frequency may be combined with respect to theother driving apparatuses 100 a to 100 c in the first example or thedriving apparatuses 100 d to 100 f in the second example.

(2-2) Driving Apparatus Adopting Biaxial Driving Method

Next, with reference to FIG. 18 to FIG. 30, of the driving apparatus 100in the examples, driving apparatuses adopting a biaxial driving method(specifically, driving apparatuses in a fifth example to an eighthexample, described later) will be described. Incidentally, the drivingapparatus adopting the biaxial driving method is a driving apparatusthat can displace the probes 12 along two axes (e.g. X axis and Y axis).In other words, the driving apparatus adopting the biaxial drivingmethod is a driving apparatus that can realize the two-dimensiondisplacement of the probes 12.

Incidentally, the same constituents as those of the driving apparatus100 a in the first example (an moreover, the driving apparatus 100 b andthe driving apparatus 100 c), the driving apparatus 100 d in the secondexample (an moreover, the driving apparatus 100 e and the drivingapparatus 1000, the driving apparatus 100 g in the third example (anmoreover, the driving apparatus 100 h and the driving apparatus 1000,and the driving apparatus 100 j in the fourth example (an moreover, thedriving apparatus 100 k) described above will carry the same numericalreferences, and the detailed explanation thereof will be omitted.

(2-2-1) Fifth Example of Driving Apparatus

Firstly, with reference to FIG. 18 to FIG. 20, a driving apparatus 100 lin a fifth example will be explained. FIG. 18 is a plan viewconceptually showing the structure of the driving apparatus 100 l in thefifth example. FIG. 19 is a plan view conceptually showing an aspectwhen a first stage 130-1 of the driving apparatus 100 l in the fifthexample shown in FIG. 18 is displaced. FIG. 20 is a plan viewconceptually showing another aspect when a second stage 130-2 of thedriving apparatus 100 l in the fifth example shown in FIG. 18 isdisplaced.

As shown in FIG. 18, the driving apparatus 100 l in the fifth example isprovided with first bases 110-1, first suspensions 120-1 which are fixedto the first bases 110-1 at their one edges and which can extend andcontract in an X-axis direction, a first stage 130-1 to which the otheredges of the first suspensions 120-1 are fixed, second suspensions 120-2which are fixed to the first stage 130-1 at their one edges and whichcan expand and contract in a Y-axis direction, and a second stage 130-2to which the other edges of the second suspensions 120-2 are fixed andwhich is provided with the plurality of probes 12. As described above,in the driving apparatus 100 l in the fifth example, the first stage130-1 is supported by the two first suspensions 120-1, and the secondstage 130-2 is supported by the two second suspensions 120-2. Moreover,the driving apparatus 100 l in the fifth example is provided with theplurality of electrodes 161 each of which is fixed to respective one ofthe first bases 110-1 and the plurality of electrodes 162 each of whichis fixed to the first stage 130-1 and each of which is grounded.Moreover, the driving apparatus 100 l in the fifth example is providedwith the electrode 141, the electrode 143 which is fixed to the firststage 130-1 and which is grounded, and the piezoelectric element 142which is disposed between the electrode 141 and the electrode 143.Incidentally, the first base 110-1, the first suspension 120-1, theplurality of electrodes 161, and the plurality of electrodes 162 aredisposed on each of the left and right sides of the first stage 130-1.Moreover, the second suspension 120-2 is disposed on each of the upperand lower sides of the second stage 130-2. In other words, the drivingapparatus 100 l in the fifth example is provided with two pairs of thefirst bases 110-1, two pairs of the first suspensions 120-1, two pairsof the plurality of electrodes 161, and two pairs of the plurality ofelectrodes 162. In the same manner, the driving apparatus 100 l in thefifth example is provided with two pairs of the second suspensions120-2.

Here, an explanation will be given on the operations of the drivingapparatus 100 l in the fifth example having the aforementionedstructure. Firstly, to each of the plurality of electrodes 161, adesired voltage is applied in desired timing from the actuator drivecircuit 22. By this, a force caused by the electrostatic force isapplied to the first stage 130-1 as the excitation force. As a result,the first stage 130-1 oscillates (i.e. is displaced) in the X-axisdirection by using the elasticity of the first suspensions 120-1, asshown in FIG. 19.

At this time, the actuator drive circuit 22 applies the desired voltageto each of the plurality of electrodes 161 in the desired timing suchthat the force for displacing the first stage 130-1 is applied in astepwise manner or in a continuous manner by a predetermined amount.

Incidentally, in the explanation below, the force applied to the base110 (or the suspensions 120 or the stage 130 as described later) fordisplacing the stage 130 in the stepwise manner or in the continuousmanner by the predetermined amount (in other words, for displacing thestage 130 in an aspect other than the aspect of oscillating the stage130 at the resonance frequency) is referred to as a “driving force”.

More specifically, the actuator drive circuit 22 applies the desiredvoltage to each of the plurality of electrodes 161 in the desired timingsuch that the driving force for realizing a tracking operation on therecording surface of the recording medium 30 by the displacement of thefirst stage 130-1 is applied. For example, if the pitch of the data(i.e. track pitch) recorded on the recording medium 30 is t, the desiredvoltage is applied to each of the plurality of electrodes 161 in thedesired timing so as to apply the driving force for displacing the firststage 130-1 by the distance t or distance Lt (wherein L is an integer of1 or more). As a result, the first stage 130-1 is displaced in thestepwise manner or in the continuous manner by the predetermined amount.

On the other hand, to the electrode 141, a desired voltage is applied indesired timing from the actuator drive circuit 22. By this, a forcecaused by a change of the shape of the piezoelectric element 142 (i.e.the piezoelectric effect) is applied to the first stage 130-1 as theexcitation force. By this, the two suspensions 120-2 which are fixed tothe first stage 130-1 at their one edges start to oscillate. As aresult, the second stage 130-2 which is fixed to the other edges of thetwo second suspensions 120-2 oscillates (i.e. is displaced) in theY-axis direction by using the elasticity of the second suspensions120-2, as shown in FIG. 20.

At this time, the actuator drive circuit 22 applies the desired voltageto the electrode 141 in the desired timing so as to apply the excitationforce for oscillating (i.e. resonating) the second stage 130-2 at theresonance frequency determined by the two second suspensions 120-2 andthe second stage 130-2. In particular, the actuator drive circuit 22applies the desired voltage to the electrode 141 in the desired timingso as to apply the excitation force for resonating the second stage130-2, with the first stage 130-1 as a reference position. As a result,the second stage 130-2 is resonated at the resonance frequencydetermined by the two second suspensions 120-2 and the second stage130-2, if it is viewed as a relative position to the first stage 130-1.

As described above, in the driving apparatus 100 l in the fifth example,it is possible to displace the second stage 130-2 in the X-axisdirection while resonating it in the Y-axis direction, by displacing thefirst stage 130-1 in the X-axis direction and by resonating the secondstage 130-2 disposed on the first stage 130-1 in the Y-axis direction.In other words, it is possible to biaxially drive the second stage 130-2(i.e. the plurality of probes 12 disposed on the second stage 130-2).Thus, it is possible to record the data onto the substantially entirerecording surface on the recording medium 30 having a rectangular shape,or to reproduce the data recorded on the substantially entire recordingsurface on the recording medium 30, by using the plurality of probes 12.

Moreover, even in the driving apparatus 100 l in the fifth example, thesecond stage 130-2 is displaced in the Y-axis direction by using theresonance as in the aforementioned driving apparatus 100 a in the firstexample and the like, so that it is possible to receive the same effectsas those received by the driving apparatus 100 a in the first example.In other words, it is possible to reduce the electric energy which isnecessary to apply the excitation force necessary for the displacementof the second stage 130-2 to the first stage 130-1. Therefore, it ispossible to displace the second stage 130-2 more efficiently, resultingin the lower power consumption of the driving apparatus 100 l. Moreover,since the behavior of the oscillation system including the second stage130-2 and the two second suspensions 120-2, which is the resonance, isused to displace the second stage 130-2, it is possible to preferablymaintain the stability of the position of the second stage 130-2. As aresult, it is possible to preferably obtain the repeatability withrespect to aspects of the displacement of the second stage 130-2. As aresult, it is possible to record the data at a desired position on therecording medium 30, or to reproduce the data recorded at the desiredposition on the recording medium 30.

Incidentally, in the driving apparatus 100 l in the fifth example, ifone of the first bases 110-1, one of the first suspensions 120-1, andthe first stage 130-1 are regarded as one driving apparatus, it ispossible to read, from the explanations and corresponding drawingsdescribed above, that the one driving apparatus including the one firstbase 110-1, the one first suspension 120-1, and the first stage 130-1has substantially the same structure as the aforementioned drivingapparatus adopting the uniaxial driving method (in particular, thedriving apparatus 100 i in the third example). Moreover, if the firststage 130-1, one of the second suspensions 120-2, and the second stage130-2 are regarded as one driving apparatus, it is possible to read,from the explanations and corresponding drawings described above, thatthe driving apparatus including the first stage 130-1, the one secondsuspension 120-2, and the second stage 130-2 has substantially the samestructure as the aforementioned driving apparatus adopting the uniaxialdriving method (in particular, the driving apparatus 100 a in the firstexample). In other words, the first stage 130-1 functions as theaforementioned stage 130 in the driving system including the first stage130-1, the first suspension 120-1, and the first stage 130-1, whereasthe first stage 130-1 functions as the aforementioned base 110 in thedriving system including the first stage 130-1, the second suspension120-2, and the second stage 130-2.

However, a second base 110-2 may be further disposed on the first stage130-1, and the second suspensions 120-2 and the second stage 130-2 maybe further disposed on the second base 110-2. Even in such construction,obviously, it is possible to preferably receive the aforementionedvarious effects.

Moreover, in the explanation about the driving apparatus 100 l in thefifth example described, the second stage 130-2 is displaced in theY-axis direction by applying the excitation force caused by thepiezoelectric effect to the first stage 130-1. However, in addition toor instead of the excitation force caused by the piezoelectric effect,the excitation force caused by the electromagnetic force and theexcitation force caused by the electrostatic force may be applied to thefirst stage 130-1. Here, with reference to FIG. 21 and FIG. 22, anexplanation will be given on a driving apparatus 100 m in which thesecond stage 130-2 is displaced in the Y-axis direction by applying theexcitation force caused by the electromagnetic force to the first stage130-1 and a driving apparatus 100 n in which the second stage 130-2 isdisplaced in the Y-axis direction by applying the excitation forcecaused by the electrostatic force to the first stage 130-1. FIG. 21 is aplan view conceptually showing the structure of the driving apparatus100 m in which the second stage 130-2 is displaced in the Y-axisdirection by applying the excitation force caused by the electromagneticforce to the first stage 130-1. FIG. 22 is a plan view conceptuallyshowing the structure of the driving apparatus 100 n in which the secondstage 130-2 is displaced in the Y-axis direction by applying theexcitation force caused by the electrostatic force to the first stage130-1. Incidentally, here, the structure for applying the “excitationforce” is explained; however, it is obvious that the structure forapplying the “driving force” may also use the piezoelectric effect, theelectromagnetic force, and the electrostatic force.

As shown in FIG. 21, the driving apparatus 100 m is provided with thecoil 151 and the magnetic pole 152 at least one of which is fixed to thefirst stage 130-1, instead of the electrode 141, the piezoelectricelement 142, and the electrode 143 provided for the driving apparatus100 l, as in the driving apparatus 100 b, the driving apparatus 100 e,and the driving apparatus 100 h described above. To the coil 151, adesired voltage is applied in desired timing from the actuator drivecircuit 22. By this, in the driving apparatus 100 m, a force caused bythe electromagnetic force is applied to the first stage 130-1 as theexcitation force. As a result, the second stage 130-2 oscillates (i.e.is displaced) in the Y-axis direction. Even in such a driving apparatus100 m, it is possible to receive substantially the same effects as thosereceived by the driving apparatus 100 l in which the aforementionedexcitation force caused by the piezoelectric effect is applied to thefirst stage 130-1.

As shown in FIG. 22, the driving apparatus 100 n is provided with theelectrode 161 and the electrode 162 which is fixed to the first stage130-1 and which is grounded, instead of the electrode 141, thepiezoelectric element 142, and the electrode 143 provided for thedriving apparatus 100 l, as in the driving apparatus 100 c, the drivingapparatus 100 f, and the driving apparatus 100 i described above. To theelectrode 161, a desired voltage is applied in desired timing from theactuator drive circuit 22. By this, in the driving apparatus 100 n, aforce caused by the electrostatic force is applied to the first stage130-1 as the excitation force. As a result, the second stage 130-2oscillates (i.e. is displaced) in the Y-axis direction. Even in such adriving apparatus 100 n, it is possible to receive substantially thesame effects as those received by the driving apparatus 100 l in whichthe aforementioned excitation force caused by the piezoelectric effectis applied to the first stage 130-1.

Incidentally, considering that the excitation force caused by theelectrostatic force is relatively small, the structure for applying theexcitation force caused by the electrostatic force to the first stage130-1 as shown in FIG. 22 may be provided with two types of drivingsources for displacing the second stage 130-2 in the Y-axis direction.The structure will be explained with reference to FIG. 23. FIG. 23 is aplan view conceptually showing the structure of a driving apparatus 100o provided with the two types of driving sources for displacing thesecond stage 130-2 in the Y-axis direction.

As shown in FIG. 23, the driving apparatus 100 o has the same structureas the above described driving apparatus 100 n. Particularly, thedriving apparatus 100 o is provided with two pairs of coils 151 andmagnetic poles 152 at least ones of which are fixed to the second stage130-2. In this case, the others of the coil 151 and the magnetic pole152 that are not fixed to the second stage 130-2 may be fixed to thefirst stage 130-1. To each of the coils 151, a desired voltage isapplied in desired timing from the actuator drive circuit 22. By this,in the driving apparatus 100 o, a force caused by the electromagneticforce can be applied to the second stage 130-2 as the excitation force.In other words, in the driving apparatus 100 o, each of the excitationforce caused by the electrostatic force and the excitation force causedby the electromagnetic force can be applied to the second stage 130-2.

Here, in the driving apparatus 100 o, at an initial stage at which thesecond stage 130-2 starts to be resonated (i.e. in a predeterminedperiod from the start of the resonance of the second stage 130-2), theexcitation force caused by the electromagnetic force is applied to thesecond stage 130-2. Then, after the initial stage, the excitation forcecaused by the electromagnetic forced is applied to the second stage130-2, as the excitation force to maintain the resonance of the secondstage 130-2.

By this, it is possible to start to resonate the second stage 130-2 byusing the relatively large excitation force caused by theelectromagnetic force, and if the behavior of the second stage 130-2 isstabilized, it is also possible to maintain the resonance of the secondstage 130-2 by using the relatively small excitation force caused by theelectrostatic force. Thus, it is possible to resonate the second stage130-2 more efficiently.

Moreover, it is possible to minimize the application of the voltage tothe coils 151 which are heat sources for the second stage 130-2. Inother words, it is possible to relatively limit or control heatgeneration caused by the coils 151 as the driving sources, in themovable portion including the two second suspensions 120-2 and thesecond stage 130-2. As a result, it is possible to preferably limit orcontrol an adverse effect of the heat on the movable portion includingthe two second suspensions 120-2 and the second stage 130-2.

Incidentally, not only in the structure for applying the excitationforce caused by the electrostatic force to the first stage 130-1 butalso in the structure for applying the excitation force caused by thepiezoelectric effect to the first stage 130-1 or the structure forapplying the excitation force caused by the electromagnetic force to thefirst stage 130-1, there may be provided with the two types of drivingsources for displacing the second stage 130-2 in the Y-axis direction.

Moreover, the aforementioned driving apparatus 100 l in the fifthexample is provided with one second stage 130-2 on the first stage130-1; however, it may be provided with a plurality of second stages130-2 on the first stage 130-1. In other words, the second stage 130-2shown in FIG. 18 may be divided. The structure will be explained withreference to FIG. 24. FIG. 24 is a plan view conceptually showing thestructure of a driving apparatus 100 p provided with the plurality ofsecond stages 130-2 on the first stage 130-1.

As shown in FIG. 24, the driving apparatus 100 p is provided with twopairs of first bases 110-1 and first suspensions 120-1, the first stage130-1, the plurality of electrodes 161, the plurality of electrodes 162,the electrode 141, the electrode 143, and the piezoelectric element 142,as in the aforementioned driving apparatus 100 l.

Particularly, the driving apparatus 100 p is provided with four secondstages 130-2 each of which has a relatively small size (specifically,each of which has a smaller size than the second stage 130-2 in thedriving apparatus 100 l), on the first stage 130-1. To each of the foursecond stages 130-2, the corresponding second suspension 120-2 is fixedat its other edge. To the first stage 130-1, each of the four secondsuspension 120-2 is fixed at its one edge.

In the driving apparatus 100 p, the actuator drive circuit 22 applies adesired voltage to the electrode 141 in desired timing so as to applythe excitation force for oscillating (i.e. resonating) each of thesecond stages 130-2 at the resonance frequency determined by thecorresponding second suspension 120-2 and each of the second stages130-2. As a result, each of the four second stages 130-2 is resonated atthe resonance frequency determined by the corresponding secondsuspension 120-2 and each of the second stages 130-2.

By this, even in the driving apparatus 100 p, it is possible to receivethe same effects as those received by the driving apparatus 100 ldescribed above.

Moreover, since the size of each of the second stages 130-2 can berelatively reduced, it is possible to relatively reduce the mass of eachof the second stages 130-2. Thus, even if the size of the secondsuspension 120-2 for supporting each of the second stages 130-2 isreduced (e.g. even if its thickness or its width is reduced), it ispossible to preferably support each of the second stages 130-2.Therefore, it is possible to lighten or miniaturize the drivingapparatus 100 p.

Incidentally, in the aforementioned driving apparatus 100 l in the fifthexample (and moreover, the driving apparatus 100 m to the drivingapparatus 100 p), the driving system in which the second stage 130-2 isresonated adopts a structure for applying the excitation force to thefirst stage 130-2 (i.e. the same structure as in the first example forapplying the excitation force to the base 110 described above). However,as in the aforementioned driving apparatus 100 d in the second example(and moreover, the driving apparatus 100 e and the driving apparatus1000, it is obvious that the excitation force may be applied to thesecond suspension 120-2. In the same manner, as in the driving apparatus100 g in the third example (and moreover, the driving apparatus 100 eand the driving apparatus 1000, it is obvious that the excitation forcemay be applied to the second stage 130-2.

Moreover, with respect to the aforementioned driving apparatus 100 l inthe fifth example (and moreover, the driving apparatus 100 m to thedriving apparatus 100 p), obviously, the various structures explained inthe first example to the fourth example described above may be applied,as occasion demands. In particular, it is effective to adjust thedeviation of the amplitude, the resonance frequency, or the like of theplurality of stages 130 for more efficient adjustment of oscillation andamplitude, by incorporating the mechanism for adjusting the resonancefrequency explained in the fourth example.

(2-2-2) Sixth Example

Next, with reference to FIG. 25, a driving apparatus 100 q in a sixthexample will be explained. FIG. 25 is a plan view conceptually showingthe structure of the driving apparatus 100 q in the sixth example.

As shown in FIG. 25, the driving apparatus 100 q in the sixth example isprovided with the first base 110-1, the first suspensions 120-1 whichare fixed to the first base 110-1 at their one edges and which canexpand and contract in the Y-axis direction, the first stage 130-1 towhich the other edges of the first suspensions 120-1 are fixed, thesecond suspensions 120-2 which are fixed to the first stage 130-1 attheir one edges and which can expand and contract in the X-axisdirection, and the second stage 130-2 to which the other edges of thesecond suspensions 120-2 are fixed and which is provided with theplurality of probes 12. As described above, in the driving apparatus 100q in the sixth example, the first stage 130-1 is supported by the twofirst suspensions 120-1, and the second stage 130-2 is supported by thetwo second suspensions 120-2. Moreover, the driving apparatus 100 q inthe sixth example is provided with coils 151-1 and magnetic poles 152-1at least ones of which are fixed to the first stage 130-1. In this case,the others of the coils 151-1 and the magnetic poles 152-1 that are notfixed to the first stage 130-1 may be fixed to the first base 110-1.Moreover, the driving apparatus 100 q in the sixth example is providedwith coils 151-2 and magnetic poles 152-2 at least ones of which arefixed to the second stage 130-2. In this case, the others of the coils151-2 and the magnetic poles 152-2 that are not fixed to the secondstage 130-2 are fixed to the first stage 130-1. Incidentally, the firstsuspension 120-1 is disposed on each of the upper and lower sides of thefirst stage 130-1. Moreover, the coils 151-1 and the magnetic poles152-1 are disposed at symmetrical positions on the left and right sidesof the first stage 130-1. Moreover, the second suspension 120-2 isdisposed on each of the left and right sides of the second stage 130-2.Moreover, the coils 151-2 and the magnetic poles 152-2 are disposed atsymmetrical positions on the upper and lower sides of the second stage130-2.

Here, an explanation will be given on the operation of the drivingapparatus 100 q in the sixth example having the aforementionedstructure. Firstly, to each of the two coils 151-1, a desired voltage isapplied in desired timing from the actuator drive circuit 22. By this, aforce caused by the electromagnetic force is applied to the first stage130-1 as the excitation force. As a result, the first stage 130-1oscillates (i.e. is displaced) in the Y-axis direction, by using theelasticity of the first suspension 120-1.

At this time, the actuator drive circuit 22 applies the desired voltageto each of the two coils 151-1 in the desired timing so as to apply theexcitation force for oscillating (i.e. resonating) the first stage 130-1at the resonance frequency determined by the two first suspensions 120-1and the first stage 130-1. As a result, the first stage 130-1 isresonated at the resonance frequency determined by the two firstsuspensions 120-1 and the first stage 130-1.

On the other hand, to each of the two coils 151-2, a desired voltage isapplied in desired timing from the actuator drive circuit 22. By this, aforce caused by the electromagnetic force is applied to the second stage130-2 as the excitation force. As a result, the second stage 130-2 isdriven (i.e. is displaced) in the X-axis direction, by using theelasticity of the second suspensions 120-2.

At this time, the actuator drive circuit 22 applies the desired voltageto each of the two coils 151-2 in the desired timing so as to apply thedriving force for displacing the second stage 130-2 in the stepwisemanner or in the continuous manner by a predetermined amount. Morespecifically, the actuator drive circuit 22 applies the desired voltageto each of the two coils 151-2 in the desired timing such that thedriving force for realizing a tracking operation on the recordingsurface of the recording medium 30 by the displacement of the secondstage 130-2 is applied. As a result, the second stage 130-2 is displacedin the stepwise manner or in the continuous manner by the predeterminedamount.

As described above, in the driving apparatus 100 q in the sixth example,the second stage 130-2 can be displaced in the X-axis direction whileresonating it in the Y-axis direction, as in the aforementioned drivingapparatus 100 l in the fifth example, by resonating the first stage130-1 in the Y-axis direction and by displacing the second stage 130-2disposed on the first stage 130-1 in the X-axis direction. In otherwords, it is possible to biaxially drive the second stage 130-2 (i.e.the plurality of probes 12 disposed on the second stage 130-2). Thus, itis possible to record the data onto the substantially entire recordingsurface on the recording medium 30 having a rectangular shape, or toreproduce the data recorded on the substantially entire recordingsurface on the recording medium 30, by using the plurality of probes 12.

Moreover, even in the driving apparatus 100 q in the sixth example, thesecond stage 130-2 is displaced in the Y-axis direction by using theresonance as in the aforementioned driving apparatus 100 a in the firstexample or the like, so that it is possible to receive the same effectsas those received by the driving apparatus 100 a in the first example.In other words, it is possible to reduce the electric energy which isnecessary to apply the excitation force necessary for the displacementof the second stage 130-2 to the first stage 130-1. Therefore, it ispossible to displace the second stage 130-2 more efficiently, resultingin the lower power consumption of the driving apparatus 100 q. Moreover,since the behavior of the oscillation system including the first stage130-1 provided with the second stage 130-2 and the two first suspensions120-1, which is the resonance, is used to displace the first stage130-1, it is possible to preferably maintain the stability of theposition of the first stage 130-1 (i.e. the second stage 130-2 disposedon the first stage 130-1). As a result, it is possible to preferablyobtain the repeatability with respect to aspects of the displacement ofthe second stage 130-2. As a result, it is possible to record the dataat a desired position on the recording medium 30, or to reproduce thedata recorded at the desired position on the recording medium 30.

Incidentally, in the driving apparatus 100 q in the sixth example, ifthe first base 110-1, one of the first suspensions 120-1, and the firststage 130-1 are regarded as one driving apparatus, it is possible toread, from the explanations and corresponding drawings described above,that the one driving apparatus including the first base 110-1, the onefirst suspension 120-1, and the first stage 130-1 has substantially thesame structure as the aforementioned driving apparatus adopting theuniaxial driving method (in particular, the driving apparatus 100 i inthe third example). Moreover, if the first stage 130-1, one of thesecond suspensions 120-2, and the second stage 130-2 are regarded as onedriving apparatus, it is possible to read, from the explanations andcorresponding drawings described above, that the driving apparatusincluding the first stage 130-1, the one second suspension 120-2, andthe second stage 130-2 has substantially the same structure as theaforementioned driving apparatus adopting the uniaxial driving method(in particular, the driving apparatus 100 i in the third example). Inother words, the first stage 130-1 functions as the aforementioned stage130 in the driving system including the first stage 130-1, the firstsuspension 120-1, and the first stage 130-1, whereas the first stage130-1 functions as the aforementioned base 110 in the driving systemincluding the first stage 130-1, the second suspension 120-2, and htsecond stage 130-2.

However, the second base 110-2 may be disposed on the first stage 130-1,and the second suspensions 120-2 and the second stage 130-2 may bedisposed on the second base 110-2. Even in such construction, obviously,it is possible to preferably receive the aforementioned various effects.

In addition, in the driving apparatus 100 q, the coils 151-1 and themagnetic poles 152-1 which are the driving sources for displacing thefirst stage 130-1 are disposed at symmetrical positions on the left andright sides of the first stage 130-1. By this, it is possible to controlthe position of the first stage 130-1 by using the two pairs of coils151-1 and magnetic poles 152-1. By adjusting the voltage (e.g. itsmagnitude, phase, or the like) applied to each of the two pairs of coils151-1 and magnetic poles 152-1, it is possible to preferably prevent adisadvantage of inclination or rotation of the first stage 130-1.

Moreover, the driving apparatus 100 q uses the electromagnetic force bythe electromagnetic interaction between ones of the coils 151-2 and themagnetic poles 152-2 that are fixed to the second stage 130-2 and theothers of the coils 151-2 and the magnetic poles 152-2 that are fixed tothe first stage 130-1, as the excitation force. In other words, theexcitation force is applied to the second stage 130-2 as a relativeforce from the resonating first stage 130-1 (i.e. the first stage 130-1as a self-resonator). Thus, the second stage 130-2, and the coils 151-2and the magnetic poles 152-2 which are the driving sources fordisplacing the second stage 130-2 are disposed on the common first stage130-1. By this, even if the first stage 130-1 is resonated, the secondstage 130-2, and the coils 151-2 and the magnetic poles 152-2 which arethe driving sources for displacing the second stage 130-2 are displacedin substantially the same aspect. Therefore, the driving apparatus 100 qcan be constructed without considering an influence of the bias in theY-axis direction caused by the resonance of the first stage 130-1. Bythis, it is possible to simplify the structures of the second stage130-2, and the coils 151-2 and the magnetic poles 152-2 which are thedriving sources for displacing the second stage 130-2. Specifically, itis possible to miniaturize the magnetic pole 152-2.

Incidentally, instead of the structure for applying the excitation forcecaused by the electromagnetic force to the second stage 130-2, even ifthe structure for applying the excitation force caused by theelectrostatic force to the second stage 130-2 is adopted, it is possibleto preferably form the plurality of comblike electrodes explained byusing FIG. 10 and the like by applying the excitation force as therelative force from the first stage 130-1 to the second stage 130-2.Moreover, instead of the structure for applying the excitation forcecaused by the electromagnetic force to the second stage 130-2, even ifthe structure for applying the excitation force caused by thepiezoelectric effect to the second stage 130-2 is adopted, it ispossible to preferably form the electrode 141, the piezoelectric element142, and the electrode 143 by applying the excitation force as therelative force from the first stage 130-1 to the second stage 130-2.

However, in addition to or instead of applying the excitation force asthe relative force from the first stage 130-1 to the second stage 130-2,the excitation force as the relative force from the first base 110-1 maybe applied to the second stage 130-2. This structure will be explainedwith reference to FIG. 26. FIG. 26 is a plan view conceptually showinganother structure of the driving apparatus 100 r in the sixth example.

As shown in FIG. 26, the driving apparatus 100 r has substantially thesame structure as the aforementioned driving apparatus 100 q. In thedriving apparatus 100 r, in particular, the others of the coils 151-2and the magnetic poles 152-2 that are not fixed to the second stage130-2 (the coils 151-2 in FIG. 26) are fixed to the first base 110-1,instead of the first stage 130-1. Therefore, the driving apparatus 100 ruses the electromagnetic force by the electromagnetic interactionbetween ones of the coils 151-2 and the magnetic poles 152-2 that arefixed to the second stage 130-2 and the others of the coils 151-2 andthe magnetic poles 152-2 that are fixed to the first base 110-1, as theexcitation force. In other words, the excitation force is applied to thesecond stage 130-2 as the relative force from the fixed first base110-1.

In the driving apparatus 100 r having the aforementioned structure, ifthe first stage 130-1 is resonated, the location of the second stage130-2 varies with respect to the other of the coils 151-2 and themagnetic poles 152-2 which are the driving sources for displacing thesecond stage 130-2. Therefore, in the driving apparatus 100 r, sincethere is no more influence of the unexpected bias in the X-axisdirection, if the displacement of the plurality of probes 12 is focusedon, the accuracy of the displacement increases.

Incidentally, the aforementioned driving apparatus 100 q in the sixthexample is provided with one second stage 130-2 on the first stage130-1; however, it may be provided with a plurality of second stages130-2 on the first stage 130-1. In other words, the second stage 130-2shown in FIG. 25 may be divided. This structure will be explained withreference to FIG. 27. FIG. 27 is a plan view conceptually showing thestructure of a driving apparatus 100 s provided with the plurality ofsecond stages 130-2 on the first stage 130-1.

As shown in FIG. 27, the driving apparatus 100 s is provided with thefirst base 110-1, the two first suspensions 120-1, the coils 151-1, andthe magnetic poles 152-1, as in the aforementioned driving apparatus 100q. Particularly, the driving apparatus 100 s is provided with the twosecond stages 130-2 each of which has a relatively small size(specifically, each of which has a smaller size than the second stage130-2 in the driving apparatus 100 q). The two second stages 130-2 arearranged in line in the X-axis direction (in other words, thedisplacement direction by the tracking operation). In other words, thetwo second stages 130-2 in the driving apparatus 100 s are obtained bydividing the second stage 130-2 in the driving apparatus 100 q along adirection substantially perpendicular to the X-axis. To each of the twosecond stages 130-2, the other edge of the corresponding secondsuspension 120-2 is connected. Each of the two second suspensions 120-2is connected to the first stage 130-1 at its one edge. Moreover, thedriving apparatus 100 s is provided with the two pairs of coils 151-2and magnetic poles 152-2, each pair of which are the driving sources fordisplacing one second stage 130-2, for each second stage 130-2independently.

In the driving apparatus 100 s, the actuator drive circuit 22 applies adesired voltage to each coil 151-2 in desired timing so as to apply theexcitation force for displacing each of the second stages 130-2. As aresult, each of the two second stages 130-2 oscillates (i.e. isdisplaced) in the X-axis direction.

By this, even in the driving apparatus 100 s, it is possible to receivethe same effects as those received by the driving apparatus 100 odescribed above.

Moreover, since the size of each of the second stages 130-2 can bereduced, it is possible to relatively reduce the mass of each of thesecond stages 130-2. Thus, even if the size of the second suspension120-2 for supporting each of the second stages 130-2 is reduced (e.g.even if its thickness or its width is reduced), it is possible topreferably support each of the second stages 130-2. Therefore, it ispossible to lighten or miniaturize the driving apparatus 100 s.

In addition, in the driving apparatus 100 s, the plurality of secondstages 130-2 are arranged to be in line in the displacement direction bythe tracking operation. Here, in the recording medium 30 having arectangular shape, there may be variations between thermal expansion inone area on the recording surface of the recording medium 30 and thermalexpansion in another area distant from the one area. Thus, there may besuch a disadvantage that the pitch of data in the one area does notmatch the pitch of data in the other area. Here, if using a drivingapparatus provided with a single second stage 130-2, the trackingoperation is performed on all the probes 12 by a common distance.Therefore, the probes 12 provided in vicinity of one edge of the secondstage 130-2 can perform data recording and reproduction in a desiredarea portion (e.g. an area portion to record the data, an area portionto reproduce the data) in the one area on the recording surface of therecording medium 30, whereas the probes 12 provided in vicinity of theother edge of the second stage 130-2 cannot perform the data recordingand reproduction in a desired area portion in the other area on therecording surfaced of the recording medium 30, which may bedisadvantageous. According to the driving apparatus 100 s, however, thetwo second stages 130-2 are provided, and each of the two second stages130-2 is displaced by the corresponding driving source of the twoindependent driving sources. Therefore, even if there are variationsbetween the thermal expansion in the one area on the recording surfaceof the recording medium 30 and the thermal expansion in the other area,the displacement of the probes 12 in each of the one area and the otherarea can be independently performed, so that it is possible topreferably perform the data recording operation and reproductionoperation with respect to each of the one area and the other area.

Incidentally, with respect to the aforementioned driving apparatus 100 qin the sixth example (and moreover, the driving apparatus 100 r to thedriving apparatus 100 s), obviously, the various structures explained inthe first example to the fifth example described above may be applied,as occasion demands.

(2-2-3) Seventh Example

Next, with reference to FIG. 28 and FIG. 29, a driving apparatus 100 tin a seventh example will be explained. FIG. 28 is a plan viewconceptually showing the structure of the driving apparatus 100 t in theseventh example. FIG. 29 is a plan view conceptually showing an aspectwhen the stage of the driving apparatus 100 t in the seven example shownin FIG. 28 is displaced.

As shown in FIG. 28, the driving apparatus 100 t in the seventh exampleis provided with the stage 130 provided with the plurality of probes 12.On each of the left and right sides of the stage 130, there are providedthe two first suspensions 120-1 each of which extends in a longitudinaldirection and each of which is fixed to the stage 130 at its one edge.Incidentally, in the explanation below, for simplification ofexplanation, the structure of the right side of the stage 130 will bedescribed; however, the left side of the stage 130 obviously has thesame structure.

The two first suspensions 120-1 are arranged to match the longitudinaldirection and the X-axis direction and to be adjacent in a lateraldirection (i.e. Y-axis direction). The other edges of the two firstsuspensions 120-1 are fixed to one edges of two driving sources 180. Thedriving sources 180 are arranged in the Y-axis direction and each ofthem is provided with an excitation force application device 181 forapplying the excitation force to displace the stage 130 in the Y-axisdirection; and a driving force application device 182 for applying thedriving force to displace the stage 130 in the X-axis direction. To theother edges of the driving sources 180, the two second suspensions 120-2are fixed which extend in the longitudinal direction. The two secondsuspension 120-2 are arranged to match the longitudinal direction andthe X-axis direction and to be adjacent in the lateral direction (i.e.Y-axis direction). The other edges of the two second suspensions 120-2are fixed to one edge of a third suspension 120-3 which can extend andcontract in the X-axis direction. The other edge of the third suspension120-3 is fixed to the base 110. Moreover, the stage 130 is connected toa tracking circuit 190 for performing the tracking operation of thestage 130 in the X-axis direction in a narrower range than the trackingoperation by the driving force application device 182.

Incidentally, the stage 130, the two first suspension 120-1, the twodriving sources 180, the two second suspensions 120-2, the thirdsuspension 120-3, and the base 110 are arranged in line in the X-axisdirection.

The stage 130 is displaced in the Y-axis direction, as shown in FIG. 29,by using the elasticity of the two first suspensions 120-1 and the twosecond suspensions 120-2. In this case, the two first suspensions 120-1actually oscillate, whereas the two second suspensions 120-2 do notoscillate or rarely oscillate. Thus, the second suspensions 120-2 may beomitted so that the driving sources 180 and the third suspension 120-3are connected. Alternatively, the second suspensions 120-2 and the thirdsuspension 120-3 may be unified.

Moreover, the stage 130 is displaced in the X-axis direction, as shownin FIG. 29, by using the elasticity of the third suspension 120-3. Theexcitation force and the driving force for displacing the stage 130 asdescribed above are applied by applying a desired voltage in desiredtiming from the actuator drive circuit 22 to the excitation forceapplication device 181 and the driving force application device 182provided for the driving source 180. Incidentally, the excitation forceapplication device 181 and the driving force application device 182 mayhave the structure for applying the driving force and the excitationforce caused by the piezoelectric element (specifically, the electrode141, the piezoelectric element 142, and the electrode 143), or thestructure for applying the driving force and the excitation force causedby the electromagnetic force (specifically, the coil 151 and themagnetic pole 152), or the structure for applying the driving force andthe excitation force caused by the electrostatic force (specifically,the electrode 161 and the electrode 162).

Moreover, the actuator drive circuit 22 applies the desired voltage inthe desired timing to the excitation force application device 181 so asto apply the excitation force for oscillating (i.e. resonating) thestage 130 at the resonance frequency determined by the stage 130 and thetwo first suspensions 120-1 on each side, i.e. four in total. As aresult, the stage 130 is resonated at the resonance frequency determinedby the stage 130 and the two first suspensions 120-1 on each side, i.e.four in total.

On the other hand, the actuator drive circuit 22 applies the desiredvoltage in the desired timing to the driving force application device182 so as to apply the driving force for displacing the stage 130 in thestepwise manner or in the continuous manner by a predetermined amount.As a result, the stage 130 is displaced in the X-axis direction in thestepwise manner or in the continuous manner by the predetermined amount.

In addition, the tracking circuit 190 displaces the stage 130 in thestepwise manner or in the continuous manner by a predetermined amountand by a finer unit than the tracking operation by the driving forceapplication device 182. As a result, the tracking operation is highlyaccurately performed on the stage 130 in the X-axis direction.

Thus, the driving apparatus 100 t in the seventh example can resonatethe stage 130 in the Y-axis direction and displace the stage 130 in theX-axis direction. In other words, it is possible to biaxially drive thestage 130 (i.e. the plurality of probes 12 disposed on the stage 130).Thus, it is possible to record the data onto the substantially entirerecording surface on the recording medium 30 having a rectangular shape,or to reproduce the data recorded on the substantially entire recordingsurface on the recording medium 30, by using the plurality of probes 12.

Moreover, even in the driving apparatus 100 t in the seventh example,since the stage 130 is displaced in the Y-axis direction by using theresonance as in the aforementioned driving apparatus 100 a in the firstexample or the like, it is possible to receive the same effects as thosereceived by the driving apparatus 100 a in the first example. In otherwords, it is possible to reduce the electric energy which is necessaryto apply the excitation force necessary for the displacement of thestage 130. Therefore, it is possible to displace the stage 130 moreefficiently, resulting in the lower power consumption of the drivingapparatus 100 t. Moreover, since the behavior of the oscillation systemincluding the stage 130 and the two suspensions 120-1, which is theresonance, is used to displace the stage 130, it is possible topreferably maintain the stability of the position of the stage 130. As aresult, it is possible to preferably obtain the repeatability withrespect to aspects of the displacement of the stage 130. As a result, itis possible to record the data at a desired position on the recordingmedium 30, or to reproduce the data recorded at the desired position onthe recording medium 30.

Incidentally, in the driving apparatus 100 t in the seventh example, thephase (or direction) of the excitation force applied by the upperdriving source 180 of the two driving sources 180 arranged in the Y-axisdirection may be shifted from the phase (or direction) of the excitationforce applied by the lower driving source 180 of the two driving sources180 arranged in the Y-axis direction. By shifting the phases of theexcitation forces applied by the two driving sources 180 arranged in theY-axis direction (i.e. the direction of the resonance) as describedabove, the amplitude of the resonance of the stage 130 (i.e. thedisplacement range in the Y-axis direction of the stage 130) can beadjusted. For example, if the upper driving source 180 applies theexcitation force for displacing the stage 130 to the upper side, and ifthe lower driving source 180 applies the excitation force for displacingthe stage 130 to the lower side (i.e. on the opposite side of thedirection in which the excitation force applied by the upper drivingsource 180 displaces the stage 130), it is possible to attenuate theamplitude of the resonance of the stage 130. In the same manner, if theupper driving source 180 applies the excitation force for displacing thestage 130 to the upper side, and if the lower driving source 180 appliesthe excitation force for displacing the stage 130 to the lower side(i.e. on the same side as the direction in which the excitation forceapplied by the upper driving source 180 displaces the stage 130), it ispossible to amplify the amplitude of the resonance of the stage 130.

The aforementioned examples shows that the phases of the two drivingsources are shifted by 180 degrees; however, the phases may be shiftednot only by 180 degrees but also by 45 degrees, by 90 degrees, by othernumeral values, or the phases may be changed continuously. In this case,slight amplitude adjustment is possible.

Incidentally, with respect to the aforementioned driving apparatus 100 tin the seventh example, obviously, the various structures explained inthe first example to the sixth example described above may be applied,as occasion demands.

(2-2-4) Eighth Example

Next, with reference to FIG. 30, a driving apparatus 100 u in an eighthexample will be explained. FIG. 30 is a plan view conceptually showingtrajectories of the displacement of the plurality of probes 12 realizedby the driving apparatus 100 u in the eighth example.

The driving apparatus 100 l in the fifth example (and moreover, thedriving apparatus 100 m to the driving apparatus 100 p), the drivingapparatus 100 q in the sixth example (and moreover, the drivingapparatus 100 r and the driving apparatus 100 s), and the drivingapparatus 100 t in the seventh example described above operate so as torealize such a state that the second stage 130-2 is resonated only inthe Y-axis direction. In other words, the second stage 130-2 is notresonated in the X-axis direction. The driving apparatus 100 u in theeighth example, however, operates so as to realize such a state that thesecond stage 130-2 is resonated in each of the Y-axis direction and theX-axis direction, while having the same structure as those of thedriving apparatus 100 l in the fifth example (and moreover, the drivingapparatus 100 m to the driving apparatus 100 p), the driving apparatus100 q in the sixth example (and moreover, the driving apparatus 100 rand the driving apparatus 100 s), and the driving apparatus 100 t in theseventh example described above.

At this time, in the driving apparatus 100 u in the eighth example, thephase of the resonance in the X-axis direction of the second stage 130-2and the phase of the resonance in the Y-axis direction of the secondstage 130-2 are shifted by approximately 90 degrees. In other words, adesired voltage is applied in desired timing from the actuator drivecircuit 22 so as to apply the excitation force by which the phase of theresonance of the second stage 130-2 in the X-axis direction and thephase of the resonance of the second stage 130-2 in the Y-axis directioncan be shifted by approximately 90 degrees. As a result, thetrajectories of the plurality of probes 12 are circular orbits as shownin FIG. 30.

In this case, the radius of the circular orbit may be changed dependingon the number of the probes 12 disposed on the second stage 130-2. Forexample, if the number of the probes 12 is relatively small, it ispreferable to increase the radius of the circular orbit because the areaportion in which the data recording and reproduction are performed byone probe 12 becomes relatively large. On the other hand, if the numberof the probes 12 is relatively large, it is preferable to reduce theradius of the circular orbit due to the area portion in which the datarecording and reproduction are performed by one probe 12 becomesrelatively small.

Even in such a driving apparatus 100 u, it is possible to properlyreceive the aforementioned various effects.

Incidentally, with respect to the aforementioned driving apparatus 100 uin the eighth example, obviously, the various structures explained inthe first example to the seventh example described above may be applied,as occasion demands.

Incidentally, the aforementioned explanation describes the example thatthe plurality of probes 12 are disposed on the stage 130 of the drivingapparatus 100; however, instead of the plurality of probes 12, therecording medium 30 may be disposed on the stage 130 of the drivingapparatus 100.

Moreover, the aforementioned explanation describes the example that thedriving apparatus 100 is applied to the ferroelectricrecording/reproducing apparatus 1; however, obviously, the drivingapparatus 100 may be applied not only to the ferroelectricrecording/reproducing apparatus 1 but also to various informationrecording/reproducing apparatuses including various probe memories.Moreover, the driving apparatus 100 may be applied not only to theinformation recording/reproducing apparatuses but also to a structureusing the probe (e.g. AFM (Atomic Force Microscopy)). Moreover, thedriving apparatus 100 may be applied to various apparatuses fordisplacing the stage in the two axes: the X-axis and the Y-axis.

Moreover, in the present invention, various changes may be made, ifdesired, without departing from the essence or spirit of the inventionwhich can be read from the claims and the entire specification. Adriving apparatus which involves such changes is also intended to bewithin the technical scope of the present invention.

INDUSTRIAL APPLICABILITY

The driving apparatus of the present invention can be applied to adriving apparatus for driving a medium or the like in a uniaxialdirection or biaxial directions so that the probe scans the surface orthe like of the medium.

1. A driving apparatus comprising: a first base portion; a first stageportion which can be displaced; a first elastic portion which connectsthe first base portion and the first stage portion and which haselasticity to displace the first stage portion in one direction; asecond stage portion which is disposed on the first stage portion, onwhich a driven object is mounted, and which can be displaced; a secondelastic portion which connects the first stage portion and the secondstage portion and which has elasticity to displace the second stageportion in other direction which is substantially perpendicular to theone direction; a first applying device for applying, to at least one ofthe first base portion and the first elastic portion, a first excitationforce for displacing the first stage portion such that the first stageportion is resonated in the one direction at a resonance frequencydetermined by the first stage portion and the first elastic portion; anda second applying device for applying a second excitation force fordisplacing the second stage portion at a phase shifted by approximately90 degrees from a phase of the displacement of the first stage portionsuch that the second stage portion is resonated in the other directionat a resonance frequency determined by the second stage portion and thesecond elastic portion.
 2. The driving apparatus according to claim 1,further comprising a second base portion which is disposed on the firststage portion, the second stage portion being disposed on the secondbase portion, the second elastic portion connecting the second baseportion and the second stage portion.
 3. The driving apparatus accordingto claim 1, wherein the first applying device applies the firstexcitation force with a period according to the resonance frequencydetermined by the first stage portion and the first elastic portion, andthe second applying device applies the second excitation force with aperiod according to the resonance frequency determined by the secondstage portion and the second elastic portion.
 4. The driving apparatusaccording to claim 1, wherein at least one of the first applying deviceand the second applying device applies at least one of the firstexcitation force and the second excitation force caused by apiezoelectric effect.
 5. The driving apparatus according to claim 1,wherein at least one of the first applying device and the secondapplying device applies at least one of the first excitation force andthe second excitation force caused by an electromagnetic force.
 6. Thedriving apparatus according to claim 1, wherein at least one of thefirst applying device and the second applying device applies at leastone of the first excitation force and the second excitation force causedby an electrostatic force.